Musnad Abu Ya'la al-Mawsili 42:88

Abu Kurayb narrated to us, Rushdin narrated to us, from ‘Amr ibn al-Harith, from Abu al-Samh, from Abu al-Haytham, from Abu Sa’id, from the Prophet, peace and blessings of Allah be upon him, who said: "Winter is the spring of the believer."