Imaam Bukhaari (rahimahullah) and Imaam Muslim (rahimahullah) narrate that Hazrat ‘Aa’ishah (radhiyallahu ‘anha) said:

أول ما بدئ به رسول اللّٰه صلى اللّٰه عليه وسلم من الوحي الرؤيا الصالحة في النوم فكان لا يرى رؤيا إلا جاءت مثل فلق الصبح

“The commencement of divine revelation upon Rasulullah (sallallahu ‘alaihi wasallam) was with pious dreams. He would not see any dream except that it would come to pass as true as clearly as the crack of dawn.”