Al-Nasāʾī likewise recorded the ḥadīth.

Al-Layth ibn Saʿd and Asbāṭ ibn Muḥammad both transmitted it.
• The first of the two—al-Layth—said: “Hishām ibn Saʿd narrated to me, from Zayd ibn Aslam, from ʿĀṣim, from men of his own clan among the Anṣār, companions of the Prophet ﷺ, who said: ‘The Messenger of Allah ﷺ said … .’” Al-Ṭaḥāwī cites this version (106).
• The other—Asbāṭ—said: “Hishām ibn Saʿd narrated to us, from Zayd ibn Aslam, from Maḥmūd ibn Labīd, from certain Companions of the Prophet ﷺ, who said: ‘The Messenger of Allah ﷺ said … .’” Aḥmad records it (4/243).

Thus, al-Layth’s chain omits Maḥmūd ibn Labīd, the teacher of ʿĀṣim ibn ʿUmar, whereas Asbāṭ’s chain omits ʿĀṣim ibn ʿUmar, the teacher of Zayd ibn Aslam.

Regarding the actual wording:
• Abū Ghassān reports it as: “mā asfartum bi-l-fajr” (do not offer the dawn prayer until the sky is bright);
• al-Layth has: “aṣbiḥū bi-ṣ-ṣubḥ fa-kullamā aṣbaḥtum bihā” (pray the dawn prayer after true morning has broken; whenever you pray it in broad daylight …);
• Asbāṭ’s version is simply: “asfirū” (perform it when it is light).

Ḥafṣ ibn Maysarah corroborated Hishām’s report from Zayd with exactly the same chain and wording as al-Layth’s narration; al-Ṭaḥāwī records it (105–106).

Another variant comes through ʿAbd al-Raḥmān ibn Zayd ibn Aslam, from his father, from Maḥmūd ibn Labīd al-Anṣārī: “The Messenger of Allah ﷺ said: ‘asfirū …’” and so on. This, however, is weakened by the fact that ʿAbd al-Raḥmān ibn Zayd is a weak transmitter.

Shuʿbah also narrated it via Abū Dāwūd, from Zayd—having dropped a link—, from Maḥmūd ibn Labīd, from Rāfiʿ ibn Khadīj, as a marfūʿ report.