Hiraṇyakaśipu advised his assistants: My dear demons, give complete protection to this boy at the gurukula where he is instructed, so that his intelligence will not be further influenced by Vaiṣṇavas who may go there in disguise.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सम्यग्विधार्यतां बालो गुरुगेहे द्विजातिभिः । विष्णुपक्षैः प्रतिच्छन्नैर्न भिद्येतास्य धीर्यथा
samyagvidhāryatāṃ bālo gurugehe dvijātibhiḥ | viṣṇupakṣaiḥ praticchannairna bhidyetāsya dhīryathā
SB 7.5.7