وَعَنْ نَافِعٍ قَالَ: إِنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ
مَرَّ عَلَى رَجُلٍ وَهُوَ يُصَلِّي فَسَلَّمَ عَلَيْهِ فَرَدَّ الرَّجُلُ كَلَامًا فَرَجَعَ إِلَيْهِ عَبْدُ اللَّهِ بْنُ عُمَرَ فَقَالَ لَهُ: إِذَا سُلِّمَ عَلَى أَحَدِكُمْ وَهُوَ يُصَلِّي فَلَا يَتَكَلَّمْ وَلْيُشِرْ بِيَدِهِ
Nafi said that Abdallah ibn Umar passed a man while he was praying and gave him a salutation to which the man uttered some words in reply. Abdallah ibn Umar went back to him and said to him, “When one of you is greeted while he is engaged in prayer he must not speak, but give a sign with his hand.”
Mishkat al-Masabih 954, Book 5, Prayer, Hadith 432. 1 min read