Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates this statement from Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him). The Prophet Muhammad (peace and blessings be upon him) said: "(Sayyiduna Musa, peace be upon him, said:) If I ask you about anything after this, then do not remain with me." In this, it is with the word of hamzah: "You have received an excuse from me."