he has sincerely performed in the court of Allah عَزَّوَجَلَّ, his prayer is accepted for the sake of that wasilah. Let us listen to an interesting incident regarding this:

Blessing of the du'a made through the Wasilah of a good deed

It is mentioned on page 139 of the book ‘Faizan-i-Riyad al-Saliheen’ published by Maktaba tul-Madinah:

Sayyiduna ‘Abdullah bin ‘Umar رَضِىَ اللهُ عَـنْهُ reports that the Messenger of Allah  صَلَّى اللهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم has stated:

In a previous era, three people were once heading somewhere when it began to rain. They entered a cave seeking cover. When they entered, a rock slid from the mountain and blocked the entrance of the cave. Seeing this, they said, “There is only one way to solve this problem, and that is to present our good deeds as a wasilah and make du'a to Allah.”

One of them said, “O Allah عَزَّوَجَلَّ! My parents were old; I did not give my children and servants milk before serving them first. One particular day, I went a long way away in search of wood. I returned to find that my parents had fallen asleep. Having brought some milk for them, I felt it inappropriate to awaken them, and I did not want to give milk to my household before my parents. Near my parents, I spent the whole night standing with a bowl of milk in my hands. When morning dawned, I offered them the milk. O Allah عَزَّوَجَلَّ! If I had performed this deed only for Your pleasure, then bring us salvation from this trouble!” By virtue of his du'a, the rock moved slightly, but not enough for them to exit.