Sunan Ibn Majah 665
سنن ابن ماجه#665SahihIt was narrated from Anas that:A man came to the Prophet; he had performed ablution and has missed a spot the size of a fingernail where water had not reached. The Prophet said to him: 'Go back and perform ablution properly
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih
In-book reference: 1:399