Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: I was with the Prophet Muhammad (peace and blessings be upon him) in a cave, and this Surah was revealed to him: «والمرسلات عرفا» So I learned it from the tongue of the Prophet (peace and blessings be upon him), even though not much time had passed since he had recited it, but I did not know on which of the two verses the Prophet (peace and blessings be upon him) ended this Surah. «فبأی حديث بعده يؤمنون» "Then in what statement after this will they believe?" Or perhaps it ended on this verse: «وإذا قيل لهم اركعوا لا يركعون» "When it is said to them, 'Bow down,' they do not bow down." Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: Meanwhile, a snake came out from a hole in front of us; we got up to kill it, but it entered another hole. The Prophet (peace and blessings be upon him) said: "You have been saved from its harm, and it has been saved from your harm."