صَحِيحُ مُسْلِمٍ
Sahih Muslim 572 f
The Book of Mosques and Places of Prayer
As-Sahw (forgetfulness) in prayer and prostrating to compensate for it
وَحَدَّثَنَاهُ يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا فُضَيْلُ بْنُ عِيَاضٍ، عَنْ مَنْصُورٍ، بِهَذَا الإِسْنَادِ وَقَالَ فَلْيَتَحَرَّ الَّذِي يُرَى أَنَّهُ الصَّوَابُ .
This hadith has been reported by Mansur with the same chain of transwitters and he said: " He should aim at what is according to him correct."
Sahih Muslim, 572 fSahihصحيح