Sunan Abi Dawud, Hadith 1494 ⓘ
Narrated Sa'd ibn AbuWaqqas: The Prophet passed by me while I was supplicating by pointing with two fingers of mine. He said: Point with one finger; point with one finger. He then himself pointed with the forefinger.
حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، حَدَّثَنَا الأَعْمَشُ، عَنْ أَبِي صَالِحٍ، عَنْ سَعْدِ بْنِ أَبِي وَقَّاصٍ، قَالَ مَرَّ عَلَىَّ النَّبِيُّ صلى الله عليه وسلم وَأَنَا أَدْعُو بِأُصْبُعَىَّ فَقَالَ " أَحِّدْ أَحِّدْ " . وَأَشَارَ بِالسَّبَّابَةِ .
also referenced under: Hadith 1499 (DarusSalam) & Book 8, Hadith 1494 (USC-MSA)