ENOfficial
Narrated Sa'd ibn AbuWaqqas: The Prophet (ﷺ) 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.
Source: sunnah.com
Other translations
Arabic
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 .
sunnah.com