In the beginning, man walked with God, and God walked with man. There was no separation. Union and harmony existed between the two, though they were distinct. Sin came and changed all that, but that is what getting back to union is all about.
And to Seth, to him also there was born a son; and he called his name Enos: then began men to call upon the name of the LORD.
Genesis 4:26
So, in the beginning, prayer not, as we understand today, part of the package. Man began to call upon the Lord after the time of Adam, after the fall, and after the time of Abel’s more righteous sacrifice.