One verse

Srimad Bhagavatam 11.18.39

11.18.39

तावत् परिचरेद् भक्त: श्रद्धावाननसूयक: । यावद् ब्रह्म विजानीयान्मामेव गुरुमाद‍ृत: ॥ ३९ ॥

tāvat paricared bhaktaḥ śraddhāvān anasūyakaḥ yāvad brahma vijānīyān mām eva gurum ādṛtaḥ

tāvat
that long
paricaret
should serve
bhaktaḥ
the devotee
śraddhā-vān
with great faith
anasūyakaḥ
being without envy
yāvat
until
brahma
spiritual knowledge
vijānīyāt
he clearly realizes
mām
Me
eva
indeed
gurum
the spiritual master
ādṛtaḥ
with great respect

Until a devotee has clearly realized spiritual knowledge, he should continue with great faith and respect and without envy to render personal service to the guru, who is nondifferent from Me.