Hadithcore
Sahih Muslim, 1253 a
sahih

Qatada said:

I asked Anas (Allah be pleased with him) as to how many Pilgrimages had been performed by Allah's Messenger (ﷺ), and he replied: One Hajj and four `Umras were performed by him. The rest of the hadith is the same.

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنِي عَبْدُ الصَّمَدِ، حَدَّثَنَا هَمَّامٌ، حَدَّثَنَا قَتَادَةُ، قَالَ سَأَلْتُ أَنَسًا كَمْ حَجَّ رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ حَجَّةً وَاحِدَةً وَاعْتَمَرَ أَرْبَعَ عُمَرٍ ‏.‏ ثُمَّ ذَكَرَ بِمِثْلِ حَدِيثِ هَدَّابٍ ‏.‏

References2 variants
In-Book Reference
Book 15, Hadith 240
USC-MSA web (English) reference
Book 7, Hadith 2880 (deprecated numbering scheme)