SB 10.18.27
niriksya tad-vapur alam ambare carat
pradipta-drg bhru-kuti-tatogra-damstrakam
jvalac-chikham kataka-kirita-kundala-
tvisadbhutam haladhara isad atrasat
Translation:
When Lord Balarama, who carries the plow weapon, saw the gigantic body of the demon as he moved swiftly in the sky — with his blazing eyes, fiery hair, terrible teeth reaching toward his scowling brows, and an amazing effulgence generated by his armlets, crown and earrings — the Lord seemed to become a little frightened.
Purport:
Srila Sanatana Gosvami explains Lord Baladeva’s so-called fear as follows: Balarama was playfully acting out the role of an ordinary cowherd boy, and to maintain the mood of this pastime He appeared slightly disturbed by the horrible demoniac body. Also because the demon had appeared as a cowherd boyfriend of Krsna’s and because Krsna had accepted him as a friend, Baladeva was slightly apprehensive about killing him. Balarama could also have been worried that since this cowherd boy was actually a demon in disguise, at that very moment another such demon might have been attacking Lord Krsna Himself. Thus the omniscient and omnipotent Supreme Lord Balarama exhibited the pastime of becoming slightly nervous in the presence of the horrible demon Pralamba.