I never saw the Prophet ﷺ fast two months consecutively except Shaban and Ramadan.
حدثنا محمد بن بشار حدثنا عبد الرحمن بن مهدي عن سفيان عن منصور عن سالم بن أبي الجعد عن أبي سلمة
ما رأيت النبي ﷺ يصوم شهرين متتابعين إلا شعبان ورمضان
[Sahih] Nasai also narrated it (4/150, no. 2177) (Fasting, chapter mentioning the hadith of Abu Salama on that matter) from Muhammad bin Bashshar with the same wording, and the hadith has sahih corroborating narrations in Nasai, no. 2178, and elsewhere.On this topic there is also a narration from Ayesha [to come: 737].