The Messenger of Allah ﷺ said, "Health and free time are two blessings from Allah which many people fail to take full advantage of."
حدثني مكي بن إبراهيم حدثنا عبد الله بن سعيد بن أبي هند أنه سمع أباه يحدث
قال رسول الله ﷺ إن الصحة والفراغ نعمتان من نعم الله مغبون فيهما كثير من الناس
Its isnad is sahih. Bukhari also related it, 11:196, from Makki bin Ibrahim, with the wording, "There are two blessings which most people undervalue, health and free time." Hafiz pointed out that Darimi related it from Makki in the same wording as in the Musnad, and that Ismaili also related it in his Mustakhraj, as noted in Fath al-Bari, and that Tirmidhi and Ibn Majah related it as well, as noted in Jami Saghir, 9280.