Synonyms of vouching

1 Syllable
vow, back
2 Syllables
support, avow, contend, sponsor, assert, cosign, avert, profess, witness, warrant, confirm, affirm, okay, prove, uphold, maintain
3 Syllables
testify, guarantee, rubber-stamp, declare, certify, assure, verify
4 Syllables
substantiate, predicate
5 Syllables
asseverate, corroborate