(7) باب تَحْرِيمِ الْكَلاَمِ فِي الصَّلاَةِ وَنَسْخِ مَا كَانَ مِنْ إِبَاحَتِهِ
Jabir reported:
We were in the company of the Messenger of Allah (ﷺ), and he sent me on an errand, and when I came back (I saw him) saying prayer on his ride and his face was not turned towards Qibla. I greeted him but he did not respond to me. As he completed the prayer, he said: Nothing prevented me from responding to your greeting but the fact that I was praying.
Reference: Sahih Muslim 540 c
In-book reference: Book 5, Hadith 47
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1102