I think best way to rehab is staying away from lifting for a while.
If anything maybe some mobility stuff and stretching but personally I would avoid anything that might just strain it even more.
Follow medical advice to begin with. In the case of some strongman buddies who had tears in the bicep tendons they did do high reps with just the olympic bar in curls (like 100)
It depends on the injury and the extent of it. Certain injuries it can help recovery to utilize those muscles slowly and steadily. Other injuries require full rest recovery and immobilization to heal.