Tirmidhi

1:
In the chain of narration of this hadith, there is a narrator, Qatadah, who is a mudallis (one who sometimes conceals his source). He has narrated from Nadr bin Anas with ‘an‘anah (using the ambiguous term "from"). Also, this hadith with these specific words is not preserved (ghayr mahfuz). ‘Amr bin ‘Asim, who is narrating from Hammam, is unique in narrating it with these words. Other students of Hammam have contradicted him and narrated it with different wording, which is as follows: ((Whoever catches one rak‘ah of the morning prayer before the sun rises, he has caught the morning prayer (i.e., within its time and reward))). Furthermore, this hadith does not explicitly indicate that whoever was unable to pray it before the morning prayer must necessarily pray it after the sun has risen. Rather, it only states that whoever was unable to pray it should pray it after the sun has risen. This means that whoever was unable to pray it within the time of performance, i.e., before the sun rises, should pray it in the time of making up (qada’), i.e., after the sun has risen. There is no evidence in this hadith that prohibits praying these two rak‘ahs after the morning prayer. This is supported by the narration of Dar Qutni, Hakim, and Bayhaqi, whose wording is: ((Whoever was unable to pray the two rak‘ahs of Fajr until the sun rises, let him pray them (after the sun has risen))).