It was narrated that 'Ali said:"A man came to the Prophet and said: 'I bathed to cleanse myself from sexual impurity, and I prayed Fajr, then I noticed a spot the size of a fingernail that the water did not reach.' The Messenger of Allah said: 'If you had wiped it that would have been sufficient for you
Hadith No. 664
Sunan Ibn Majah
Gradings:
Al-Albani:
Very Daif
Muhammad Fouad Abd al-Baqi:
Daif
Shuaib Al Arnaut:
Daif
Zubair Ali Zai:
Daif