Sayyidina Abu Hurairah (RA) reported that Allah’s Messenger ﷺ went to Ubayy ibn Ka’b. He called out. “O Ubbay!” He was engaged in salah and turned but did not answer. He shortened his salah and then went to Allahs Messenger ﷺ and said, “As-salammu alikum, O Messenger of Allah ﷺ ”! He said, “Wa alika salaam! What prevented you, O Ubayy, from answering me when I called you”? He said, “O Messenger of Allah ﷺ , I was engaged in salah.” He said, “Have you not observed that which Allah has revealed to me: “Respond to Allah and to His Messenger ﷺ when he (the Messenger) calls you.” (Al-Quran 8:24). He said, “Yes indeed. I will not do it again, Insha Allah.” He asked, “Would you love that I teach you a surah that has not been revealed in the Torah, not in the Injil, not in the Zabur and not in the Qur’an, the like of it.” He answered, “Yes, O Messenger of Allah ﷺ . So, he asked, “How do you recite in salah”? He said, “We recite the ummul Qar’an.” So, Allah’s Messeneger said, “By Him in Whose hand is my soul, nothing has been revealed like it in the Turah, the Injil, the Zabur and the Qur’an. It is the sab’am minal mathani and the mighty Qur’an that is given to me.” --------------------------------------------------------------------------------