Allah has prescribed the prayer through the word of your Prophet (ﷺ) as four rak'ahs when resident, two when travelling, and one when danger is present.
Sahih Muslim Book 6, Hadith 6
← Previous Hadith I said to 'Umar b. al-Khattab, and the rest of the hadlth is the same.

Sahih Muslim Book 6, Hadith 5 Next Hadith → Allah has prescribed the prayer by the tongue of your Apostle (ﷺ) as two rak'ahs for the traveller, four for the resident, and one in danger.

Sahih Muslim Book 6, Hadith 7