testify vs cite

testify is not a noun while cite is a noun.

Word	Noun	Adjective	Verb	Adverb
testify	No	No	Yes	No
cite	Yes	No	Yes	No

As verbs, cite is a hyponym of testify; that is, cite is a word with a more specific, narrower meaning than testify:

Other hyponyms of testify include attest, certify, demonstrate, evidence, manifest, presume, abduce, adduce.

testify (noun)	cite (noun)
	a short note recognizing a source of information or of a quoted passage

testify (verb)	cite (verb)
give testimony in a court of law	make reference to
provide evidence for	commend
	repeat a passage from
	refer to for illustration or proof
	advance evidence for
	call in an official matter, such as to attend court
	refer to