SB 10.47.24
dana-vrata-tapo-homa
japa-svadhyaya-samyamaih
sreyobhir vividhais canyaih
krsne bhaktir hi sadhyate
Translation:
Devotional service unto Lord Krsna is attained by charity, strict vows, austerities and fire sacrifices, by japa, study of Vedic texts, observance of regulative principles and, indeed, by the performance of many other auspicious practices.
Purport:
Srila Visvanatha Cakravarti explains the processes described here as follows. Dana: donations given to Lord Visnu and His devotees. Vrata: observing vows such as Ekadasi. Tapas: renunciation of sense gratification for Krsna’s sake. Homa: fire sacrifices dedicated to Visnu. Japa: privately chanting the holy names of the Lord. Svadhyaya: study and recitation of Vedic texts such as the Gopala-tapani Upanisad.