Caitanya Caritamrta—Madhyalila-15.108—- For conditioned souls to do devotional service, deity worship is necessary.
928)-Whether I know without proper initiation all my devotional activities are useless! Taught by Srila Prabhupada!
The Hari-bhakti-viläsa (2.6) quotes the following injunction from the Visnu-yämala:
adiksitasya vämoru krtam sarvam nirarthakam
pasu-yonim aväpnoti diksä-virahito janah
“‘Unless one is initiated by a bona fide spiritual master, all his devotional activities are useless. A person who is not properly initiated can descend again into the animal species.’”
Hari-bhakti-viläsa (2.10) further quotes:
ato gurum pranamyaivam sarva-svam vinivedya ca
grhniyäd vaisnavam mantram diksä-pürvam vidhänatah
“‘It is the duty of every human being to surrender to a bona fide spiritual master. Giving him everything—body, mind and intelligence—one must take Vaisnava initiation from him.’” ————–