Here begins the narration known as the Ḥadīth al-Futūn, which relates the story of Moses in full, from beginning to end.
Imām Abū ʿAbd al-Raḥmān al-Nasāʾī records in the Book of Tafsīr of his Sunan, under the verse in Sūrat Ṭā Hā, “You killed a man, so We delivered you from sorrow and tried you with many trials” (20:40):
(The Ḥadīth of the Trials)
He reports: ʿAbd Allāh ibn Muḥammad told us; Yazīd ibn Hārūn informed us; Aṣbagh ibn Zayd narrated; al-Qāsim ibn Abī Ayyūb related; Saʿīd ibn Jubayr said:
I asked ʿAbd Allāh ibn ʿAbbās about Allah’s words to Moses, “and We tried you with many trials,” saying, “What are those trials?”
He replied, “Begin a new day, Ibn Jubayr, for this is a long account.”
When morning came I went to Ibn ʿAbbās to receive the report he had promised about the trials, and he said:
“Pharaoh and his courtiers reviewed Allah’s promise to Abraham—peace be upon him—that He would raise from his descendants prophets and kings. Some of them said, ‘The Children of Israel are certain of this and are waiting for it; they thought it referred to Joseph son of Jacob.’ When Joseph died they said, ‘This is not what Abraham was promised.’
“Pharaoh asked, ‘What do you suggest?’ They consulted and agreed to send men carrying knives throughout the Israelites to slaughter every male newborn they found, and they did so.
“When they saw that the elders of the Israelites were dying of natural causes while the young were being slain, they said, ‘You are close to exterminating the Israelites, and then you yourselves will have to do the work and service they now perform for you. Kill every male infant one year so their numbers decline, and spare them the next so the youngsters may grow up to replace the elders who die. Those you spare will not become so many that you fear their numbers, nor will the nation perish because of those you kill and yet need.’ They settled on that policy.
“Moses’ mother conceived Aaron in the year when boys were not killed, and she gave birth to him openly and safely. The following year she conceived Moses—peace be upon him—and anxiety and grief filled her heart. That, Ibn Jubayr, is one of the trials that befell her …"