śāstre yuktau ca nipuṇaḥ
sarvathā dṛḍha-niścayaḥ
prauḍha-śraddho 'dhikārī yaḥ
sa bhaktāv uttamo mataḥ
śāstre - in the revealed scriptures; yuktau - in logic; ca - also; nipuṇaḥ - expert; sarvathā - in all respects; dṛḍha-niścayaḥ - who is firmly convinced; prauḍha - deep; śraddhaḥ - who has faith; adhikārī - eligible; yaḥ - who; saḥ - he; bhaktau - in devotional service; uttamaḥ - highest; mataḥ - is considered.
This verse appears in the Bhakti-rasāmṛta-sindhu (1.2.17), by Śrīla Rūpa Gosvāmī.