Hadith: The Prophet (may Allah's peace and blessings be upon him) did not observe a voluntary prayer more regularly than the two Rak‘ahs of Fajr

عن عائشة بنت أبي بكر الصديق رضي الله عنهما قالت: «لم يَكُن النبي صلى الله عليه وسلم على شيء من النَّوَافل أشد تَعاهُدَاً منْهُ على ركْعَتَي الفَجْرِ». وفي رواية: «رَكْعَتا الفَجْرِ خيرٌ منَ الدُّنيا وما فيها».
[صحيح] - [الرواية الأولى: متفق عليها. والرواية الثانية: رواها مسلم]

‘Ā'ishah bint Abu Bakr As-Siddīq (may Allah be pleased with her) reported: The Prophet (may Allah's peace and blessings be upon him) did not observe a voluntary prayer more regularly than the two Rak‘ahs of Fajr. Another narration reads: "The two Rak‘ahs of Fajr are better than the entire world.”
Sahih/Authentic. - [Muslim]

Explanation

This Hadīth shows the importance of the two confirmed supererogatory Rak‘ahs of Fajr. ‘Ā'ishah (may Allah be pleased with her) mentioned that the Prophet (may Allah's peace and blessings be upon him) affirmed them and emphasized their significance by what he did, as he used to regularly observe them, and by saying that they are better than the world and everything therein.