(3) باب كَيْفَ فُرِضَتِ الصَّلاَةُ .
It was narrated that Ibn 'Abbas said:
"The Salah was enjoined on the lips of the Prophet (ﷺ), four Rak'ahs while resident, and two while traveling, and one Rak'ah during times of fear."
Reference: Sunan an-Nasa'i 456
In-book reference: Book 5, Hadith 9
English translation: Vol. 1, Book 5, Hadith 457