Responding to the call of Nabi (Sallallahu Alayhi Wasallam) even if one was engaged in Salaah
Q: A family member recently heard a lecture in which the speaker made a comment that if you do not think of nabi salaalaahu alaihi wa sallam in your namaaz, your namaaz is invalid. The speaker furhter presented a hadith as his proof in which he only mentioned that a sahaabi was performing namaaz when Nabi (Alaihis Salaam) called him and he failed to reply.
Is there any such hadeeth, if yes, what is the complete hadith with the explanation?