Having comprehended the value of “knowledge and pratice”, we should know that there is no benefit in any other than these two precious gems, for the rest are either necessities of life or something extra.  We have to discuss these two in order to make them clear.

First-Necessities of life
  Seeking necessities of life is not a sin rather it is considered as a prayer, the Holy Prophet of Islam has said:
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170.  “One who labors for the livelihood of his family is as a fighter in the way of God.”
  Imam Ali (AS) has said:
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171.  “Do deal-May God give you blessings-for I have head from the Holy Prophet (SAW) as saying: sustenance has ten parts, nine of it is deal and one part is in other things.”
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172.  “The biggest sin of a man is to let his family’s right go to waste.”
  The Holy Prophet (SAW) has said:
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173.  “Accursed is one who lets his family’s rights go to waste.”
  One should note that certain rules must be observed:
  First, one should go after Halal (lawful) and shun Haram (unlawful) and doubtful business, for engaging in a business which is neither Halal nor Haram will make man to engage in Haram.
  The Holy Prophet (SAW) has said:
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174.  “One who does not care how he earns his livelihood, God does not care from which way he will be thrown into Hell either.”
  Secondly, one should be content with what he earns.  For instance, if he can work all day long for one Dinar, but he knows that his expense is one third of Dinar, he should work a third of the day and spent the rest in prayer.  Saving expenses for a year is permissible but more than that is not good. 
  Sheikh Sadooq has reported on the authority of the Holy Prophet (SAW):
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175.  “One who is in good health, is secure and has the expenses of a day and night, has the whole world with him: O son of Ja-sham, the expenses necessary are first: the food which removes your hunger, and secondly the clothes which cover your body.  If you possess a house it is good and if a riding vehicle is added to them, that would be excellent.  But if they are not available, a simple food is sufficient, for if it is more than that, you are either answerable for it or exposed to punishment.”
  Thirdly, he should renounce avarice which is blameworthy, for it leads to the commitment of erroneous deeds and sometimes unlawful ones.  One must know that the subsistence of God’s servant has been divided.  Hence neither avarice increases it nor contentment decreases it.
  It has been reported on the authority of the Infallibles (AS):
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176.  “Useless effort and avarice will not increase lawful sustenance and God’s grant.”
  The Holy Prophet (SAW) in the farewell Hajj said:
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177.  “O people! I informed you about what brings you to paradise and keeps you away from Hell, and encouraged you about those deeds.  I also bewared you of what brings you to Hell and keeps you away from paradise.  Know that Gabriel inspired into my heart that: No one dies but he has fully received his sustenance.  Therefore avoid being worldly.  Do not ever seek your sustenance through unlawful way if it is delayed.  Surely God has divided lawful and not unlawful sustenance among people.  One Who has forbearance and observes piety, will receive lawful sustenance.  And one who is impudent, hasty and earns his livelihood in an unlawful way, will have sustenance decreased to the same extent and he will be questioned too on the Day of Judgment.
  One day the Holy Prophet (SAW) said to one of his companions:
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178.  “How do you feel if you live long enough to see a nation who saves the expenses of one year but their belief in God and Ressurrection is weak?  Do not ever grief in the morning for night nor grief in night for the morning when you don’t know whether you will be alive or dead tomorrow?”
So far we have discussed livelihood.  As for expenses, we should say that you have to observe moderation as well as economization in relation to what you earn.  DO not ever be extravagant, for God in verse 27 of the Quranic chapter, the Israelites (Bani Israel), says:
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“Surely the squanderers are the fellows of the shaitans.”
  The Holy Prophet (SAW) says:
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179.  “One who is extravagant will be made destitute by God.”
  The Holy Prophet (SAW) also says:
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180.  “One who is moderate will never become destitute.”
  One has the following duties against one’s dependents:
1-  Against oneself
  One must avoid overeating, for the Holy Prophet (SAW) has said:
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181.  “For the children of Adam, a few morsels which can keep him alive are sufficient.  So when he needs food, let him devote one third of his stomach to food, one third to drinks and the last third to breathing.”
  The Holy Prophet (SAW) has said:
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182.  “In the Day of Judgment only those people starve who are the most gluttonous in this world.”
  Gluttony has the following pests:
-It will cause hard-heartedness.
-It keeps body from worship.
-It keeps man from keeping vigil in prayer.
-It keeps man from recommended prayer after midnight.
  Those who are gluttonous are found in dirty places but those with a light stomach are found in mosques.

2-  Against family
  One must observe moderation and not be strict to them, rather he should be lenient to them and whenever he gives a promise, he has to keep it to make his family happy. 
  It has been reported on the authority of Imam Moosa (AS):
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183.  “Whenever you give a promise to children, keep it, for they think you are the giver of sustenance and God does not become so wrathful against men as he does because of unfair treatment of women and children.”  
  A praiseworthy tradition is that man should buy fruits for his family especially on Friday about which Imam Ali (AS) has said:
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184.  “Come home to your family members with fruits every Friday night so that they will become happy about Friday.”  
3-  Against parents
  Respecting parents especially mothers is recommended.  In this relation Imam Sadeq (AS) has said:
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185.  “The best deeds are: Prayer in its proper time, respecting one’s parents and fighting in the way of God.”  
  A Hadith says:  
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186.  “When prophet Moses (AS) was invoking God, he saw a man praying under the Throne of God.  Moses (AS) envied him saying: O God! How have you promoted this man to such position?  God said: This man had two virtues, first he did good to his parents and secondly he was not a talebearer.”  
  A man came to the Holy Prophet (SAW) saying: Is there any way for me to repent, the Holy Prophet said:  
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187.  “Is one of your parents still living?”  
  He said: Yes, my father.  
  The Holy Prophet said:     *      *
“Go and do good to him.”  
  When the man returned, the Holy Prophet said:    *       *
"Had he a mother, it would be better.”  
   The Holy Prophet has also said:  
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188.  “One who wishes to have a long life and have his sustenance increased, must do good to his parents, for taking care of them is considered as a prayer.”  
  A man said to Imam Sadeq (AS): I have an old father whom I carry whenever he wants to relieve himself.  The Holy Prophet (SAW) said:  
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189.  “Keep on doing it, for this deed of yours will serve as a shield against fire of Hell.”  
  Imam Sadeq (AS) also said:  
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190.  “What keeps you from doing good to your living or dead parents?  Perform prayer, keep fast, and give charity on their behalf, for it will benefit both you and them.  God too will reward you for your good deeds.”