SB 3.12.50

ṛṣīṇāṁ bhūri-vīryāṇām
 api sargam avistṛtam
jñātvā tad dhṛdaye bhūyaś
 cintayām āsa kaurava
Word for word: 
ṛṣīṇām — of the great sages; bhūri-vīryāṇām — with great potency; api — in spite of; sargam — the creation; avistṛtam — not extended; jñātvā — knowing; tat — that; hṛdaye — in his heart; bhūyaḥ — again; cintayām āsa — he began to consider; kaurava — O son of the Kurus.
Translation: 
O son of the Kurus, when Brahmā saw that in spite of the presence of sages of great potency there was no sufficient increase in population, he seriously began to consider how the population could be increased.