Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah Almighty created Adam (peace be upon him) in his form, his height was sixty cubits. When Allah Almighty created him, He said: Go and greet that group of angels sitting there and listen carefully to what they reply to you, for these (words) will be the greeting for you and your descendants. (He went and) said: As-salamu Alaikum. They replied: As-salamu Alaika wa Rahmatullah. That is, they added the words 'wa Rahmatullah.' When a person enters Paradise, he will enter in the form (and stature) of Adam (peace be upon him). But (from the birth of Adam till) today, the height and stature have been decreasing."