Śrīmad-Bhāgavatam · Text 7.10.4
Who is speaking and story frame
नान्यथा तेऽखिलगुरो घटेत करुणात्मन: ।
यस्त आशिष आशास्ते न स भृत्य: स वै वणिक् ॥ ४ ॥
nānyathā te ’khila-guro
ghaṭeta karuṇātmanaḥ
yas ta āśiṣa āśāste
na sa bhṛtyaḥ sa vai vaṇik
Otherwise, O my Lord, O supreme instructor of the entire world, You are so kind to Your devotee that You could not induce him to do something unbeneficial for him. On the other hand, one who desires some material benefit in exchange for devotional service cannot be Your pure devotee. Indeed, he is no better than a merchant who wants profit in exchange for service.
Read Śrīla Prabhupāda's purport on Vedabase.io