(44, 45) باب عَقْلِ الأَصَابِعِ
It was narrated from Ibn 'Abbas:
"This and this are the same: The little finger and the thumb (sahih) (ID)
Reference (ID): Sunan an-Nasa'i 4848 (ID)
In-book reference (ID): Book 45, Hadith 143 (ID)
English translation (ID): Vol. 5, Book 45, Hadith 4852 (ID)