Overall meaning : Your Lord, Muhammad, knows that you sometimes stand in prayer for less than two-thirds of the night, and sometimes for half the night and at other times for one-third of it, as do some of your believing companions. Allah alone determines the measure and hours of the night and the day. He knows that you, believers, cannot keep an exact count of its hours, and so He has turned to you mercifully and lightened your burden regarding the night prayer. Pray, therefore, as much as may be easy for you without a specific amount.
He knows that some of you are ill who are too weak to perform the night prayer, and others who travel through the land in search of Allah bounty to earn their livelihoods, and yet others who fight against the unbelievers for the cause of Allah to make His religion reign supreme. Pray, then, at night as much as may be easy for you. Observe and attend to the prescribed prayers, pay the obligatory charity (zakat) to the poor and needy who are eligible for it, and give alms from your lawful earnings for the sake of Allah alone. Whatever good you do in this life you will surely find its reward multiplied with Allah in the next. Seek Allah’s forgiveness, for Allah is All-Forgiving, All-Merciful.