The meaning of the Prophet's words: "The two months of 'Id cannot both be incomplete" Sahih Muslim 1089 a

Arabic hadith text
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ أَخْبَرَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ خَالِدٍ، عَنْ عَبْدِ الرَّحْمَنِ، بْنِ أَبِي بَكْرَةَ عَنْ أَبِيهِ، - رضى الله عنه - عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏شَهْرَا عِيدٍ لاَ يَنْقُصَانِ رَمَضَانُ وَذُو الْحِجَّةِ ‏"
Translation
The son of Abu Bakra reported it on the authority of his father that the Messenger of Allah (ﷺ) had said

The two months of 'Id, Ramadan and Dhu'l-Hijja (are not incomplete).