Hadith 1443
´It was narrated that Ibn 'Abbas said:` "Allah, the Mighty and Sublime, enjoined the prayer on the tongue of your Prophet (ﷺ): While a resident four (rak'ahs), while traveling two, and at times of fear one."
Hadith 2521
´It was narrated from Al-Ju'aid:` "I heard As-Sa'ib bin Yazid say: 'During the time of Allah's messenger, the Sa' was equal to a Mudd and third of the Mudd you use today, and the Sa' of today has become large."' (Sahih) Abu 'Abdur-Rahman (An-Nasa'i) said: And Ziyad bin Ayyub narrated it to me.