(52) باب النَّهْىِ عَنِ الْخَاتَمِ، فِي السَّبَّابَةِ
It was narrated that 'Ali said:
"The Messenger of Allah [SAW] said to me: 'Say: O Allah, guide me and make me steadfast,' and he forbade me to put a ring on this one and this one" - and Bishr (one of the narrators) pointed to his forefinger and middle finger. And 'Asim said: "One of the two of them."
Reference: Sunan an-Nasa'i 5212
In-book reference: Book 48, Hadith 173
English translation: Vol. 6, Book 48, Hadith 5215