SB 1.5.1
suta uvaca
atha tam sukham asina
upasinam brhac-chravah
devarsih praha viprarsim
vina-panih smayann iva
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Suta Gosvami said: Thus the sage amongst the gods [Narada], comfortably seated and apparently smiling, addressed the rsi amongst the brahmanas [Vedavyasa].
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Narada was smiling because he well knew the great sage Vedavyasa and the cause of his disappointment. As he will explain gradually, Vyasadeva’s disappointment was due to insufficiency in presenting the science of devotional service. Narada knew the defect, and it was confirmed by the position of Vyasa.