Ubayy ibn Ka’b (r.a.) said to the Messenger of Allah, peace be upon him,

“O Messenger of Allah, I do a lot of prayer on you. How much prayer should I allot for you?”

He said, ‘However much you like.’

I said, ‘A quarter?’

He said, ‘However much you like, but if you do more, it will be better for you.’

I said, ‘A half?’

He said, ‘However much you like, but if you do more, it will be better for you.’

I said, ‘Two-thirds?’

He said, ‘However much you like, but if you do more, it will be better for you.’

I said, ‘I will allot all my prayer for you.’

He said, ‘Then you will be spared from worry and forgiven your wrong action.’”

- [al-Tirmidhi and al-Haakim]