Definition of "asseveration"

[…] no man is believ’d a jot the more for all the Aſſeverations, Damnings and Swearings he makes: […]

1693, Daniel Defoe, An Essay upon Projects, London: […] R. R. for Tho[mas] Cockerill, […], published 1697, page 240

Custom-houſe oaths and political oaths are but little regarded even by ſome who pretend to principles of honeſty and religion: and a Quaker’s aſſeveration is with us juſtly put upon the ſame footing with the oath of any other perſon.

a. 1777, David Hume, part XII, in Dialogues Concerning Natural Religion, [London?], published 1779, page 146

[…] on all such occasions Mr. Grimwig plants, fishes, and carpenters with great ardour, doing everything in a very singular and unprecedented manner; but always maintaining, with his favourite asseveration, that his mode is the right one.

1838, Boz [pseudonym; Charles Dickens], “And Last”, in Oliver Twist; or, The Parish Boy’s Progress. […], volume III, London: Richard Bentley, […], page 310

The true oath consists in the simple asseveration, uttered in perfect consciousness and under a sense of the presence of God, before Him, and in Him.

1861, J[ohann] P[eter] Lange, translated by Alfred Edersheim, Theological and Homiletical Commentary on the Gospel of St Matthew. Specially Designed and Adapted for the Use of Ministers and Students., volume I, Edinburgh: T. & T. Clark, […]; London: Hamilton, Adams, and Co.; Dublin: John Robertson, page 228

After this homily which he delivered with much warmth of asseveration Mr Mulligan in a trice put off from his hat a kerchief with which he had shielded it.

1922 February, James Joyce, “[Episode 14: Oxen of the Sun]”, in Ulysses, Paris: Shakespeare and Company, […], part II [Odyssey], page 385