Kathir b. ‘Abdallah on his father’s authority quoted his grandfather as saying that at the two festivals the Prophet (ﷺ) said “God is most great” seven times in the first <i>rak'a</i> before reciting from the Qur’an, and five times in the last one before reciting. Tirmidhi, Ibn Majah and Darimi transmitted it.

وَعَنْ كَثِيرِ بْنِ عَبْدِ اللَّهِ عَنْ أَبِيهِ عَنْ جَدِّهِ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَبَّرَ فِي الْعِيدَيْنِ فِي الْأُولَى سَبْعًا قَبْلَ الْقِرَاءَةِ وَفِي الْآخِرَةِ خَمْسًا قَبْلَ الْقِرَاءَةِ. رَوَاهُ التِّرْمِذِيّ وَابْن مَاجَه والدارمي