Allah's Messenger (S) said: "Whoever did not pray the two Rak'ah (before) Fajr then let him pray them after the sun has risen."
Jami` at-Tirmidhi Book 2, Hadith 276
← Previous Hadith "Allah's Messenger (S) went out and the Iqamah was called for the Salat so I prayed As-Subh with him. Then the Prophet (S) turned and found me performing Salat so he said: 'Easy O Qais! Are there two prayers together?' I said: 'O Messenger of Allah! I did not perform the two Rak'ah (before) Fajr.' He said: 'Then there is no harm.'"

Jami` at-Tirmidhi Book 2, Hadith 275 Next Hadith → "The Prophet (S) would pray four Rak'ah before Az-Zuhr and two Rak'ah after it."

Jami` at-Tirmidhi Book 2, Hadith 277