SB 8.19.18

śrī-balir uvāca
aho brāhmaṇa-dāyāda
 vācas te vṛddha-sammatāḥ
tvaṁ bālo bāliśa-matiḥ
 svārthaṁ praty abudho yathā
Synonyms: 
śrī-baliḥ uvāca — Bali Mahārāja said; aho — alas; brāhmaṇa-dāyāda — O son of a brāhmaṇa; vācaḥ — the words; te — of You; vṛddha-sammatāḥ — are certainly acceptable to learned and elderly persons; tvam — You; bālaḥ — a boy; bāliśa-matiḥ — without sufficient knowledge; sva-artham — self-interest; prati — toward; abudhaḥ — not knowing sufficiently; yathā — as it should have been.
Translation: 
Bali Mahārāja said: O son of a brāhmaṇa, Your instructions are as good as those of learned and elderly persons. Nonetheless, You are a boy, and Your intelligence is insufficient. Thus You are not very prudent in regard to Your self-interest.
Purport: 

The Supreme Personality of Godhead, being full in Himself, actually has nothing to want for His self-interest. Lord Vāmanadeva, therefore, had not gone to Bali Mahārāja for His own self-interest. As stated in Bhagavad-gītā (5.29), bhoktāraṁ yajña-tapasāṁ sarva-loka-maheśvaram. The Lord is the proprietor of all planets, in both the material and spiritual worlds. Why should He be in want of land? Bali Mahārāja rightly said that Lord Vāmanadeva was not at all prudent in regard to His own personal interests. Lord Vāmanadeva had approached Bali not for His personal welfare but for the welfare of His devotees. Devotees sacrifice all personal interests to satisfy the Supreme Personality of Godhead, and similarly the Supreme Lord, although having no personal interests, can do anything for the interests of His devotees. One who is full in himself has no personal interests.