(2) That he deliver it while standing.

Several ḥadīths address this point.

The first: ʿAbd al-Raḥmān ibn Abī Laylā said, “The prayer passed through three stages. Our companions related to us that the Messenger of Allah ﷺ said, ‘I have been pleased that the prayer of the Muslims— or, he said, of the believers— be one and the same …’ He then narrated the incident: A man from the Anṣār came and said, ‘Messenger of Allah, when I returned—having noticed how concerned you were—I saw a man who seemed to be wearing two green garments. He stood at the mosque and gave the adhān, then he sat briefly, after which he stood again and did the same, except that this time he proclaimed, “The prayer has begun.” Had it not been that people would say I was awake and not asleep …’ The Messenger of Allah ﷺ replied, ‘Allah has shown you something good; tell Bilāl to give the call.’ ʿUmar then said, ‘I too saw what he saw, but since he came before me I felt shy to speak.’

Abū Dāwūd recorded it through Shuʿbah, from ʿAmr ibn Murrah, who said, ‘I heard Ibn Abī Laylā narrate it.’ The chain is authentic; its transmitters are those relied upon by the six major collections.

Al-Ṭaḥāwī also transmitted it through Zayd ibn Abī Unaysah, from ʿAmr ibn Murrah, with a similar wording, and Ibn Abī Shaybah cited it in his Muṣannaf, as mentioned in Naṣb al-Rāyah.