Jamieson, Fausset and Brown on Revelation 14:4

4. virgins--spiritually (Mt 25:1); in contrast to the apostate Church, Babylon (Re 14:8), spiritually "a harlot" (Re 17:1-5; Is 1:21; contrast 2Co 11:2; Ep 5:25-27). Their not being defiled with women means they were not led astray from Christian faithfulness by the tempters who jointly constitute the spiritual "harlot."

follow the Lamb whithersoever he goeth--in glory, being especially near His person; the fitting reward of their following Him so fully on earth.

redeemed--"purchased."

being the--rather, "as a first-fruit." Not merely a "first-fruit" in the sense in which all believers are so, but Israel's 144,000 elect are the first-fruit, the Jewish and Gentile elect Church is the harvest; in a further sense, the whole of the transfigured and translated Church which reigns with Christ at His coming, is the first-fruit, and the consequent general ingathering of Israel and the nations, ending in the last judgment, is the full and final harvest.