that Thabit bin Ad-Dahhak had informed him that he was one of those who had given the Pledge of allegiance (of Al-Hudaibiya) beneath the Tree.
أَخْبَرَهُ أَنَّهُ بَايَعَ النَّبِيَّ ﷺ تَحْتَ الشَّجَرَةِ
that Thabit bin Ad-Dahhak had informed him that he was one of those who had given the Pledge of allegiance (of Al-Hudaibiya) beneath the Tree.
أَخْبَرَهُ أَنَّهُ بَايَعَ النَّبِيَّ ﷺ تَحْتَ الشَّجَرَةِ