CC Ādi 5.173

caitanya-prabhute tāṅra sudṛḍha viśvāsa
nityānanda-prati tāṅra viśvāsa-ābhāsa
Word for word: 
caitanya-prabhute — unto Lord Caitanya; tāṅra — his; su-dṛḍha — fixed; viśvāsa — faith; nityānanda-prati — unto Lord Nityānanda; tāṅra — his; viśvāsa-ābhāsa — dim reflection of faith.
Translation: 
My brother had firm faith in Lord Caitanya but only a dim glimmer of faith in Lord Nityānanda.