Green’s Dictionary of Slang

swear v.

SE in slang uses

In phrases

swear blind (v.) [blind adv.1 ]

[1930s+] to affirm emphatically and without qualification.

swear by (v.)

[mid-18C+] to accept as the truth, to have complete faith in.

swear off (v.) (also swear off on) [? one’s oath of self-denial]

[late 19C+] to give up, to abandon, to renounce.

swear on a stack of Bibles (a mile high) (v.) (also swear on a stack of Bibles as high as one’s head, ...on a truckload of Bibles, ...on a bag of boomerangs)

[mid-19C+] (orig. US) to make an elaborate or exaggerated oath, usu. in the face of another’s disbelief.

swear to beef

[2000s] (US black) a general interrogatory phr.