twice its length is the hadith of Jabir concerning the account of Gabriel (1).
However, the stronger view on this issue is the hadith of Abdullah ibn Amr ibn al-As, in which the Messenger ﷺ said: “The time for the afternoon prayer lasts so long as the sun has not turned yellow” (2)—that is, so long as it has not become yellow. This will generally be later than the point at which the shadow of everything becomes twice its length. This additional extent is to be accepted, since the hadith is in Sahih Muslim and is a statement of the Messenger ﷺ.
The hadith of Gabriel may be answered by saying that he began the prayer with the Prophet ﷺ when the shadow of everything had become twice its length, and that by the time it was prayed and completed, the sun would have turned yellow—especially during the winter days, when the time for the afternoon prayer is short. Whether or not this reconciliation is sound, accepting the additional extent is necessary, for accepting the additional extent entails accepting both what is additional and what is lesser, whereas accepting the lesser entails disregarding the additional extent. Accordingly, we say that the time for the afternoon prayer lasts until the sun turns yellow.
The evidence that its time extends until sunset is the Prophet’s ﷺ statement: “Whoever catches one rak'ah of the afternoon prayer before the sun sets has caught the afternoon prayer” (3). This is an explicit text establishing that the time extends until