كتاب الصلاة
2  
The Book of Prayer
Bulugh al-Maram 225
Narrated Ibn 'Umar (RA):
I asked Bilal (RA), "How did you observe the Prophet (ﷺ) replying to their (the Companions) salutation while he was engaged in prayer?" He (Bilal) said: "He used to do this way," and he (Bilal) demonstrated by spreading his palm. [Reported by Abu Dawud and at-Tirmidhi. The latter graded it Sahih (authentic)].
وَعَنْ اِبْنِ عُمَرَ ‏- رَضِيَ اَللَّهُ عَنْهُمَا‏-]قَالَ] : { قُلْتُ لِبِلَالٍ : كَيْفَ رَأَيْتُ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-يَرُدَّ عَلَيْهِمْ حِينَ يُسَلِّمُونَ عَلَيْهِ , وَهُوَ يُصَلِّي ? قَالَ : يَقُولُ هَكَذَا , وَبَسَطَ كَفَّهُ } أَخْرَجَهُ أَبُو دَاوُدَ , وَاَلتِّرْمِذِيُّ وَصَحَّحَهُ 1
Reference : Bulugh al-Maram 225
In-book reference : Book 2, Hadith 225
English translation : Book 2, Hadith 223
Hadith Text
Reference