Al-Muzzammil · 73:20

20. Your Lord, O Messenger, knows that you sometimes spend less than two thirds of the night in prayer, sometimes you stand for half the night, sometimes a third, and a group of the believers stand with you. Allah determines the night and day and counts their hours. He (may He be glorified) knows that you are not able to count and keep a record of its hours, and thus standing for the most part of it seeking the required will be difficult for you. He therefore has accepted your repentance. So pray at night as much as is easy for you. Allah knows that some of you, O believers, may be ill and constrained by illness - others will be travelling seeking Allah’s provision, and others will be fighting the disbelievers seeking Allah’s pleasure and to promote Allah’s word. For these people standing in prayer at night is difficult, so pray at night as much as is easy for you and discharge the obligatory prayer in the most perfect manner. Give the charity of your wealth and spend from your wealth in Allah’s path. Whatever good you send forward for yourselves, you will find it to be better and greater in reward. Seek forgiveness from Allah. Allah Forgiving towards those of His servants who repent and He is merciful to them.