#They said to him

"Then they said to Abraham"

#He said, "I will certainly return to you

The word "He" refers to the man whom Abraham called "Lord" in [[:en:bible:notes:gen:18:03|18:3]].

#in the springtime

"when this same season comes next year" or "about this time next year" (UDB)

#and see

The word "see" here alerts us to pay attention to the surprising information that follows.

#in the tent doorway

"at the opening of the tent" or "at the entrance of the tent"