Jamieson, Fausset and Brown on Hebrews 13:3

3. Remember--in prayers and acts of kindness.

bound with them--by virtue of the unity of the members in the body under one Head, Christ (1Co 12:26).

suffer adversity--Greek, "are in evil state."

being yourselves also in the body--and so liable to the adversities incident to the natural body, which ought to dispose you the more to sympathize with them, not knowing how soon your own turn of suffering may come. "One experiences adversity almost his whole life, as Jacob; another in youth, as Joseph; another in manhood, as Job; another in old age" [Bengel].