What kind or type of food did the prophet saws eat before closing his fast at sehri? and what did he eat to open his fast at iftar?
In the name of Allah, Most Compassionate, Most Merciful.
The sunnah of suhoor would be fulfilled by eating a small or large quantity of food, or even just by drinking a sip of water. Abu Sa'id al-Khudri reported that the Messenger of Allah said: "The pre-dawn meal is blessed, so do not neglect it even if you only take a sip of water. Verily, Allah and the angels pray for those who have pre-dawn meals." This is related by Ahmad. (Fiqhus Sunnah: 3.130A)
Salman ibn Amir (radi allahu anhu) narrates that the Prophet (sallal lahu alayhi wa sallam) said: “When one of you is fasting, he should break his fast with dates; but if he cannot get any, then (he should break his fast) with water, for water is purifying.” (Abu Dawood: 975)
In another Hadith Anas ibn Malik (radi allahu anhu) narrates that the Apostle of Allah (sallal lahu alayhi wa sallam) used to break his fast before praying with some fresh dates; but if there were no fresh dates, he had a few dry dates, and if there were no dry dates, he took some mouthfuls of water. (Abu Dawood: 976)
In conclusion it is preferable to close or open fast with dates. If that is not available then with water or anything else that is available.
And Allah knows best.
Darul Ifta Birmingham