The Prophet ﷺ was not more diligent in observing any voluntary prayer than he was with the two rakahs before Fajr.
لم يكن النبي ﷺ على شيء من النوافل أشد منه تعاهدا على ركعتي الفجر.
Bukhari narrated it in tahajjud (1169), and Muslim in travelers (724:94), both of them through Yahya bin Saeed, from Ibn Jurayj, who said, Ata told me, from Ubayd bin Umayr, from Ayesha, and he related it.