1) Affirmed forcefully 2) Affirmed solemnly 3) Asseverated 4) Attested 5) Blasphemed 6) Cursed 7) Cussed 8) Declared on a stack of Bibles 9) Delivered an oath 10) Dropped an F-Bomb 11) Gave a shit 12) Gave an oath 13) Gave an oath, worse off 14) Gave earnest assurances 15) Gave one''s word 16) Gave testimony Found on https://www.crosswordclues.com/clue/swore