SB 6.7.21

śrī-brahmovāca
aho bata sura-śreṣṭhā
 hy abhadraṁ vaḥ kṛtaṁ mahat
brahmiṣṭhaṁ brāhmaṇaṁ dāntam
 aiśvaryān nābhyanandata
Word for word: 
śrī-brahmā uvāca — Lord Brahmā said; aho — alas; bata — it is very astonishing; sura-śreṣṭhāḥ — O best of the demigods; hi — indeed; abhadram — injustice; vaḥ — by you; kṛtam — done; mahat — great; brahmiṣṭham — a person fully obedient to the Supreme Brahman; brāhmaṇam — a brāhmaṇa; dāntam — who has fully controlled the mind and senses; aiśvaryāt — because of your material opulence; na — not; abhyanandata — welcomed properly.
Translation: 
Lord Brahmā said: O best of the demigods, unfortunately, because of madness resulting from your material opulence, you failed to receive Bṛhaspati properly when he came to your assembly. Because he is aware of the Supreme Brahman and fully in control of his senses, he is the best of the brāhmaṇas. Therefore it is very astonishing that you have acted impudently toward him.
Purport: 

Lord Brahmā recognized the brahminical qualifications of Bṛhaspati, who was the spiritual master of the demigods because of his awareness of the Supreme Brahman. Bṛhaspati was very much in control of his senses and mind, and therefore he was a most qualified brāhmaṇa. Lord Brahmā chastised the demigods for not properly respecting this brāhmaṇa, who was their guru. Lord Brahmā wanted to impress upon the demigods that one’s guru should not be disrespected under any circumstances. When Bṛhaspati entered the assembly of the demigods, they and their king, Indra, took him for granted. Since he came every day, they thought, they did not need to show him special respect. As it is said, familiarity breeds contempt. Being very much displeased, Bṛhaspati immediately left Indra’s palace. Thus all the demigods, headed by Indra, became offenders at the lotus feet of Bṛhaspati, and Lord Brahmā, being aware of this, condemned their neglect. In a song we sing every day, Narottama dāsa Ṭhākura says, cakṣu-dāna dila yei, janme janme prabhu sei: the guru gives spiritual insight to the disciple, and therefore the guru should be considered his master, life after life. Under no circumstances should the guru be disrespected, but the demigods, being puffed up by their material possessions, were disrespectful to their guru. Therefore Śrīmad-Bhāgavatam (11.17.27) advises, ācāryaṁ māṁ vijānīyān nāvamanyeta karhicit/ na martya-buddhyāsūyeta: the ācārya should always be offered respectful obeisances; one should never envy the ācārya, considering him an ordinary human being.