Verb
To invoke in an oath; to swear upon.
(idiomatic) To trust wholeheartedly.
I swear by my Petit Larousse when it comes to learning French.
He swears by cream of tartar to make the meringues stiff.
We swear by the Quran and Sunnah, and we will not compromise with any infidel.... Islam is the truth and all else is falsehood. Abu Bakar Bashir
So long as my body lives, and yours -- we are one flesh," he whispered, "And when my body shall cease, my soul will still be yours. Claire -- I swear by my hope of heaven, I will not be parted from you. Diana Gabaldon
I swear by God, the Peerless, the Incomparable, the True One: for no other reason hath He - the supreme Testimony of God - invested Me with clear signs and tokens than that all men may be enabled to submit to His Cause. Báb
I swear by the most holy Essence of God - exalted and glorified be He - that in the Day of the appearance of Him Whom God shall make manifest a thousand perusals of the Bayán cannot equal the perusal of a single verse to be revealed by Him Whom God shall make manifest. Báb
Let every American, every lover of liberty, every well-wisher to his posterity swear by the blood of the Revolution never to violate in the least particular the laws of the country, and never to tolerate their violation by others. Abraham Lincoln
Swear by your brunt shins. Scottish Proverb