It is that when the Messenger of Allah (peace be upon him) calls people to matters that give life, it is obligatory for them to respond to his call, even if they are performing prayer.

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) passed by Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) while he was praying, so the Prophet (peace and blessings of Allah be upon him) called him. He turned towards the Prophet (peace and blessings of Allah be upon him) (and continued his prayer), then (after completing the prayer) he came to the service of the Messenger of Allah (peace and blessings of Allah be upon him) and said, "O Messenger of Allah, «‏‏‏‏السَّلامُ عَلَیْکَ» ‏‏‏‏." The Prophet (peace and blessings of Allah be upon him) said: " «‏‏‏‏وَعَلَيْك السَّلام» ‏‏‏‏" "O Ubayy, when I called you, what prevented you from coming?" He replied, "O Messenger of Allah, I was praying." The Prophet (peace and blessings of Allah be upon him) said: "Did you not find this command in the Book of Allah" «‏‏‏‏يَا أَيُّهَا الَّذِينَ آمَنُوا اسْتَجِيبُوا لِلَّهِ وَلِلرَّسُولِ إِذَا دَعَاكُمْ لِمَا يُحْيِيكُمْ» ‏‏‏‏ "O you who believe, obey Allah and His Messenger when He calls you to that which gives you life." He replied, "Why not (this command is certainly present), may my parents be sacrificed for you." Sayyiduna Ubayy says, "InshaAllah, I will not be negligent in this in the future." This is the hadith of Ibn Wahb.