Usama bin Zayd used to fast during the sacred months. The Messenger of Allah ﷺ said to him, "Fast Shawwal." So he abandoned fasting the sacred months and continued fasting Shawwal until he died.
حدثنا محمد بن الصباح حدثنا عبد العزيز الدراوردي عن يزيد بن عبد الله بن أسامة بن الهاد
أن أسامة بن زيد كان يصوم أشهر الحرم فقال له رسول الله ﷺ صم شوالا فترك أشهر الحرم ثم لم يزل يصوم شوالا حتى مات
No references are available.
[Its isnad is daif] Muhammad bin Ibrahim Taymi is trustworthy, but Hafiz said in Tahdheeb*, "He transmitted with an incomplete chain (mursal) from Usayd bin Hudayr and Usamah."