It is narrated from Sayyiduna Qays bin Sa'd bin Ubadah (may Allah be pleased with him) that his father had presented him to the Prophet (peace and blessings be upon him) to serve him. He narrates: I was praying two rak'ahs when the Prophet (peace and blessings be upon him) came to me, gestured to me with his (blessed) foot and said: "Shall I not tell you about one of the doors (the key to one of the doors) of Paradise?" I said: Certainly, O Messenger of Allah! He (peace and blessings be upon him) said: "(Say:) 'La hawla wa la quwwata illa billah' (There is no power and no strength except with Allah)." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it. Imam al-Hakim says that this establishes that it is permissible for a father to present his child for service (of the elders); it also shows the virtue of Qays bin Sa'd (may Allah be pleased with him), that he served the Prophet (peace and blessings be upon him) so much that he became like his right hand (sahib al-shurat), and then he also stood by the Commander of the Faithful, Ali bin Abi Talib (may Allah be pleased with him), in every circumstance, until he was martyred before him at the Battle of Siffin.