Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
Sayyiduna Ubayy bin Ka`b said to the Prophet ﷺ: “I bestow prayers upon you and do so in abundance. How many of my prayers should I make for you?” What is the meaning of this statement?
The scholars say there are several possible meanings. The meaning which is closest to the wording of the hadith is ‘how much of the reward of my prayers should I donate to you?’
A second possible meaning is ‘how many of all my duas should I make for you?’
A third meaning is ‘how much of my time should I spend bestowing prayers upon you?’
The first meaning encompasses the other two meanings.
When Ubayy said that he would make all his prayers for the Prophet, the Prophet said to him: “If you do that, your worries will be removed and your sins will be forgiven.”
 Narrated by Ahmad, al-Tirmidhi and al-Hakim