From Sahih Bukhari (Hadith 6227):
Narrated Abu Huraira:The Prophet (ﷺ) said, "Allah created Adam in His picture, sixty cubits (about 30 meters) in height. When He created him, He said (to him), "Go and greet that group of angels sitting there, and listen what they will say in reply to you, for that will be your greeting and the greeting of your offspring." Adam (went and) said, 'As-Salamu alaikum (Peace be upon you).' They replied, 'AsSalamu-'Alaika wa Rahmatullah (Peace and Allah's Mercy be on you) So they increased 'Wa Rahmatullah' The Prophet (ﷺ) added 'So whoever will enter Paradise, will be of the shape and picture of Adam Since then the creation of Adam's (offspring) (i.e. stature of human beings is being diminished continuously) to the present time
Reference: Bukhari 6227