Majma al-Zawaid — Hadith 11917

Sayyiduna Anas (may Allah be pleased with him) relates that the Prophet (peace and blessings be upon him) said: "There is no harm upon you if you do not marvel at anyone until you see what his end will be. A doer may do righteous deeds for a long period of his life, deeds such that if he died upon them he would enter Paradise, and then he turns and begins doing evil deeds. And a servant may do evil deeds for a long period, such that if he died upon them he would go to Hell, but then he turns and begins doing righteous deeds. When Allah, the Blessed and Exalted, intends good for a servant, He employs him before his death." The people said: "O Messenger of Allah, how does He employ him?" The Prophet (peace and blessings be upon him) said: "He grants him the ability to do a righteous deed and then takes his soul upon it."
Ahmad, Abu Ya'la and al-Bazzar recorded it, and al-Tabarani in al-Mu'jam al-Awsat, and its narrators are the narrators of the Sahih.