Srimad Bhagavatam Canto 10, Chapter 11, Text 42

SB 10.11.42

tam vatsa-rupinam viksya
vatsa-yutha-gatam harih
darsayan baladevaya
sanair mugdha ivasadat
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When the Supreme Personality of Godhead saw that the demon had assumed the form of a calf and entered among the groups of other calves, He pointed out to Baladeva, “Here is another demon.” Then He very slowly approached the demon, as if He did not understand the demon’s intentions.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The import of the words mugdha iva is that although Krsna knows everything, here He pretended that He did not understand why the demon had entered among the calves, and He informed Baladeva by a sign.
 
Srimad Bhagavatam Canto 10, Chapter 11, Text 41
Srimad Bhagavatam Canto 10, Chapter 11, Text 43