SB 10.78.25-26

ṛṣer bhagavato bhūtvā
 śiṣyo ’dhītya bahūni ca
setihāsa-purāṇāni
 dharma-śāstrāṇi sarvaśaḥ
adāntasyāvinītasya
 vṛthā paṇḍita-māninaḥ
na guṇāya bhavanti sma
 naṭasyevājitātmanaḥ
Synonyms: 
ṛṣeḥ — of the sage (Vyāsadeva); bhagavataḥ — the incarnation of Godhead; bhūtvā — becoming; śiṣyaḥ — a disciple; adhītya — studying; bahūni — many; ca — and; sa — together with; itihāsa — epic histories; purāṇāni — and Purāṇas; dharma-śāstrāṇi — the scriptures describing the religious duties of man; sarvaśaḥ — fully; adāntasya — for him who is not self-controlled; avinītasya — not humble; vṛthā — vainly; paṇḍita — a scholarly authority; māninaḥ — thinking himself; na guṇāya — not leading to good qualities; bhavanti sma — they have become; naṭasya — of a stage performer; iva — like; ajita — unconquered; ātmanaḥ — whose mind.
Translation: 
Although he is a disciple of the divine sage Vyāsa and has thoroughly learned many scriptures from him, including the lawbooks of religious duties and the epic histories and Purāṇas, all this study has not produced good qualities in him. Rather, his study of the scriptures is like an actor’s studying his part, for he is not self-controlled or humble and vainly presumes himself a scholarly authority, though he has failed to conquer his own mind.
Purport: 

One might argue that Romaharṣaṇa committed an innocent mistake when he failed to recognize Lord Balarāma, but such an argument is refuted here by Lord Balarāma’s strong criticism.