It is narrated from Qays bin Qahd (may Allah be pleased with him) that he came while the Prophet (peace and blessings be upon him) was leading the Fajr prayer, so he prayed with him. When he (peace and blessings be upon him) gave the salam, he stood up and prayed the two (sunnah) rak'ahs of Fajr. The Prophet (peace and blessings be upon him) said to him: "What are these two rak'ahs?" He replied: I had not prayed them before Fajr. So he (peace and blessings be upon him) remained silent and did not say anything. Qays bin Qahd al-Ansari (may Allah be pleased with him) is a Companion, and the chain reaching him is sahih (authentic) on the condition of the two Shaykhs. Muhammad bin Ibrahim al-Taymi has also narrated it from Qays bin Qahd:

It is narrated from Sayyiduna Qays bin Qahd (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) saw a man praying two rak'ahs after the Fajr prayer. The Messenger of Allah (peace and blessings be upon him) said: "Are you praying the Fajr prayer twice?" The man replied: I had not prayed the two rak'ahs that come before it, so I have prayed them now. The narrator said: So the Messenger of Allah (peace and blessings be upon him) remained silent about him.