When Lord Brahmā heard everything from the demigods and the members who had attended the sacrifice, he replied: You cannot be happy in executing a sacrifice if you blaspheme a great personality and thereby offend his lotus feet. You cannot have happiness in that way.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तदाकर्ण्य विभुः प्राह तेजीयसि कृतागसि । क्षेमाय तत्र सा भूयान्न प्रायेण बुभूषताम्
tadākarṇya vibhuḥ prāha tejīyasi kṛtāgasi | kṣemāya tatra sā bhūyānna prāyeṇa bubhūṣatām
SB 4.6.4