SB 10.18.13
kvacin nrtyatsu canyesu
gayakau vadakau svayam
sasamsatur maha-raja
sadhu sadhv iti vadinau
Translation:
While the other boys were dancing, O King, Krsna and Balarama would sometimes accompany them with song and instrumental music, and sometimes the two Lords would praise the boys, saying, “Very good! Very good!”