He (Dr. Zaid) says that God, after removing an additional charity requirement in 58:12, and after removing an additional prayer requirement in 73:20, is reminding the Muslims of the basic requirement in these two areas that are still in place.
I respectfully disagree with Dr. Zaid. There is no additional charity
requirement in 58:12. God has described it as
صدقة (Sadaqa), which in Islamic law means
voluntary charity. Mandatory charity is called Zakah.
One may argue that the Zakah verse, 9:60, calls the Zakah Sadaqa. There are many reasons for this. Zakah means purifier and grower, which Sadaqa also does. Sadaqa means proof of faith, which Zakah also does. All mandatory Zakah is Sadaqa, but not all Sadaqa is mandatory Zakah. Verse 9:60 is actually about
whom all charity goes to, mandatory or voluntary. God does not specify in 9:60 how much to give or the fact that this is the required Zakah. We only know that 9:60 is about Zakah because the Prophet, peace be upon him, told us.
As for 73:20, there is no additional prayer requirement lifted from the believers. There was none in the first place, as the requirement was directed at the Prophet (PBUH) only.
What is interesting is that what Dr. Zayd thought was an abrogation of extra worship, could very well be understood as
correction to those who thought so! In other words, staying up at night praying was never a mandate on Muslims and 73:20 was revealed to make that clear. And offering a charity before private audience with the Prophet (PBUH) was never a mandate and 58:13 was revealed to make that clear.