Misinterpretation of 73:20
The words in 73:20 are often quoted to justify various night Salat that are not authorised by God in the Quran.
Indeed, your Lord knows that you stay up a little less than two-thirds of the night, and half of it, and one-third of it, along with a group among those with you. And God determines the night and the day. He knows that you will not be able to keep its count, so He has redeemed you. So read what you can of the Quran. He knows there will be among you those who are ill, and others travelling the land seeking God's bounty, and others fighting in the cause of God. So read what you can of it, observe the Salat, give the Zakat, and lend God a good loan. Whatever good you put forward for yourselves, you will find it with God, better and greater in reward. And ask God for forgiveness. Indeed, God is Forgiver, Merciful. 73:20
The above Quranic words are used by some scholars to state that the prophet used to stay up long hours of the night, together with those with him, observing additional night Salat. Those are the Salat known as: Nawafil, Taraweeh, Tahhajud and Qiyam al-layl.
It is then added that since God commanded us to follow the prophet, it becomes mandatory for all Muslims to observe these additional night Salat just like the prophet did.
The words in 73:1-7 are also quoted to say that it was God who commanded the prophet to stay up to observe those additional Salat:
O you enwrapped one, arise during the night, except a little, half of it, or reduce from it a little, or add to it a little, and recite the Quran at a measured pace. We will cast upon you a heavy Word. The night vigil is more productive and more receptive to what is to be told. During the day, you are long occupied with other matters. 73:1-7
The words "arise during the night" are specifically quoted to make the point.
FIRST
The Quranic law decreed by God is given through clear Quranic words in the Quran and not through personal claims derived from personal understanding of Quranic words.
The Quran authorises only three Salat, and in accordance with 4:103, each one of these three Salat is given its precise time in the Quran. The three Salat and their times are as follows:
1- The Fajr Salat is named in 24:58 and its time is given in 11:114.
2- The Wusta Salat is named in 2: 238 and its time is given in 17:78.
3- The Isha Salat is named in 24:58 and its time is given in 11:114.
Other than these three Salat there are no names of any other Salat nor times given for any additional Salat in the Quran.
For more details see: Three Salat
SECOND
The claim that the first seven verses in Sura 73 confirm that God commanded prophet Muhammad to stay up to observe additional night Salat can easily be debunked.
O you enwrapped one, arise during the night, except a little, half of it, or reduce from it a little, or add to it a little, and recite the Quran at a measured pace. We will cast upon you a heavy Word. The night vigil is more productive and more receptive to what is to be told. During the day, you are long occupied with other matters. 73:1-7
1- The word Salat is not mentioned anywhere in the above verses. Needless to say, when the subject of a Quranic verse is the Salat, the word Salat is always mentioned.
2- The first seven verses of Sura 73 address prophet Muhammad alone and the subject of these first seven verses was the Quranic revelation that was coming upon the prophet.
3- The words "We will cast upon you a heavy Word" speak about the Quranic revelation that was being revealed to Muhammad. They do not speak about the Salat.
4- Sura 73 was one of the earliest Suras to be revealed (3rd in order) and so it was of paramount importance that the prophet would understand why the revelation was coming to him at night. The following words provided the explanation:
The night vigil is more productive and more receptive to what is to be told. During the day, you are long occupied with other matters.
Furthermore, the words "what is to be told" confirm that the verses speak about what was to be told/given to the prophet and not a Salat that the prophet was to offer.
5- The prophet was also given instructions as to how the revelation was to be recited when delivering it to his people. The words "recite the Quran at a measured pace" were part of the message of those seven verses.
6- The reason for which God was commanding the prophet to stay up parts of the night was to receive the Quranic revelation which was described as a "heavy Word".
Therefore, to quote those seven verses to justify the additional un-Quranic night Salat is to manipulate God's words in order to serve a personal un-Quranic agenda.
THIRD
When we look at the words in 73:20, and how they are quoted to justify the additional un-Quranic Salat, we find that the words in the verse confirm the exact opposite of what is being claimed.
Indeed, your Lord knows that you stay up a little less than two-thirds of the night, and half of it, and one-third of it, along with a group among those with you. And God determines the night and the day. He knows that you will not be able to keep its count, so He has redeemed you. So read what you can of the Quran. He knows there will be among you those who are ill, and others travelling the land seeking God's bounty, and others fighting in the cause of God. So read what you can of it, observe the Salat, give the Zakat, and lend God a good loan. Whatever good you put forward for yourselves, you will find it with God, better and greater in reward. And ask God for forgiveness. Indeed, God is Forgiver, Merciful. 73:20
1- The opening words say that God knows that the prophet and a group with him rise for long periods of the night (for prayers).
2- God tells the prophet that he and those with him "you will not be able to keep its count" in other words, they would not be able to keep it up.
3- Here we come to the keywords with which God ascertains the correct meaning. God tells the prophet "He has redeemed you". These words are very important. The act of redemption by God necessitates a prior error, mistake or sin committed by the human being. The question is what was God pardoning the prophet for? The only information given in the verse before the words of redemption tells us that the prophet was staying long hours of the night for prayers with those with him.
4- The words "He knows there will be among you those who are ill, and others travelling the land seeking God's bounty, and others fighting in the cause of God." reveal the reason why God redeemed and pardoned the prophet. The prophet of God, with undoubtedly good intentions was burdening the believers by making them stay long hours of the night doing extra prayers. This burden was not called for knowing that there would be those who are sick and others weary from travel among them.
Had these additional prayers been authorised or required by God, there would have been no reason to redeem or pardon the prophet.
5- The words continue to say that those who wish to do extra good work should "Read what you can of it (Quran), observe the Salat, give the Zakat, and lend God a good loan." In other words, the prophet and those with him are asked to do only what God decreed for them.
6- Evidently, the words "observe the Salat" here do not speak of unauthorised Salat that are not found in the Book of God, but they speak of the Salat which is authorised by God in the Quran.