Narrated Abu Huraira: Allah's Messenger (ﷺ) said, "If anyone of you can get one rak`a of the `Asr prayer before sunset, he should complete his prayer. If any of you can get one rak`a of the Fajr prayer before sunrise, he should complete his prayer."
The chain is ordered from the source of the saying to the compiler: 1 = the speaker/first transmitter, the following links those who passed it on in turn, and at the bottom al-Bukhari who compiled the work. Click a narrator to list every hadith in which he appears; the number in parentheses is how many hadiths across the collections on this site the narrator appears in.