Edited extract from Imam Ghazali's Arabic Book 'Ayyuhal Walad' from His Three-Volumes Collection of Short Books 'Majmu'a Rasail Imam Ghazali'
My dear beloved son!
Do not forget me in your supplications (Du'a). You have desired that I should write a supplication (Du'a) for you [that you can always recite], so you should search for supplications in the book of ahadith (the traditions of Prophet Muhammad 
[especially] in Sahah Sitta (the six most authentic collections of the traditions of Prophet Muhammad and memorize them. Likewise, many supplications have come [to us] from the methods of the Ahl al-Bayt (the family of Prophet Muhammad , so search for them there. Recite the following [supplication], in particular, after every prayer (Salat):
"O my Allah! I desire from You the completion (abundance/perfection) of Your blessings and from purity (inner and outer) I desire its permanence and from Your mercy [I desire] its inclusion [in all matters] and from health [I desire] its attainment and from sustenance [I desire] its increase and from life [I desire] its happiness and from life [I desire] its real success and from good qualities [I desire] their completion and from your rewards [I desire] the reward which is the most common and from your plenitude [I desire] the plenitude which is the sweetest and from your favors [I desire] the favor which is the most plentiful and from deeds [I desire] the deed which is the best and from knowledge [I desire] the knowledge which is the most beneficial and from the sustenance [I desire] the sustenance which is the most plentiful.
O my Allah! You become ours (grant us benefits) and do not burden us (protect us from harms). O my Allah! Grant us salvation when we die and reform our deeds and grant us safety in your days and nights and grant us your mercy in our houses and in our possessions and cover our sins and fault with the cover of your forgiveness and do us favors by correcting all our faults [inner and outer] and give us confidence and reliance on You.
O my Allah! Grant us perseverance and persistence in our Din (religion/Path to God). Save us from such deeds in the world that will become a source of shame (humiliation) on the Day of Judgment and lessen the burdens of our sins on us and grant us a life of the pious ones and be sufficient to us in all our affairs and protect us from the evil of the evildoers. Liberate us and our ancestors, from the fire of Hell, from loans, and from oppression O You the Victorious One (Ya Aziz)! O You the Forgiving One (Ya Ghaffar)! O You the Generous One (Ya Kareem)! O You the Coverer of faults (Ya Sattar)! O You the Tolerant One (Ya Haleem)! O You the Powerful One (Ya Jabbar)! O You the Magnificent One (Ya Azeem)! O You the One Who Punishes (Ya Qahhar)! O Allah! O Allah! O Allah! O You the Compassionate One (Ya Rahman) in this world! O You the Merciful One (Ya Raheem) in the life hereafter! O You the Supreme Merciful One (Ya Arhum ur-Rahimeen)! You are the Grantor of the Excessive Mercy! And may the mercy and blessings of Allah always descend on Muhammad (Peace and blessings of Allah be upon him) who is the best of all [of God's] creations [from eternity to eternity] and on his descendants and on his companions. All praises are solely due to Allah the Lord of all the Universes (Rabb ul-'Alameen)."
This comes to end with the help of the Absolute Sovereign (Al-Malik) and the Giver of all (Al-Wahhab)!
[especially] in Sahah Sitta (the six most authentic collections of the traditions of Prophet Muhammad