Bayhaqi 15913 — Those between whom there is no retaliation

Amr bin Shu'ayb narrates from his father, and he from his grandfather (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "The blood of the believers is equal, one to another; the protection granted by the lowest of them is honoured; the farthest of them may grant protection on their behalf; they will be helped against those besides them; the strong among them shares (the spoils) with the weak, and the one who rushes ahead (to fight) with the one who stays behind; a believer is not to be killed in return for a disbeliever, nor one who has a covenant while his covenant lasts."