A.T. Robertson Commentary Mark 13:27

"And then shall he send forth the angels, and shall gather together his elect from the four winds, from the uttermost part of the earth to the uttermost part of heaven." — Mark 13:27 (ASV)

Shall gather together his elect (επισυναξε τους εκλεκτους αυτου). This is the purpose of God through the ages.

From the uttermost part of the earth to the uttermost part of heaven (απ' ακρου γης εως ακρου ουρανου). The Greek is very brief, "from the tip of earth to the tip of heaven." This precise phrase occurs nowhere else.