भयाद्रणादुपरतं मंस्यन्ते त्वां महारथाः। येषां च त्वं बहुमतो भूत्वा यास्यसि लाघवम् ॥

bhayād raṇād uparataṁ mansyante tvāṁ mahā-rathāḥ yeṣhāṁ cha tvaṁ bahu-mato bhūtvā yāsyasi lāghavam

The great car-warriors will think thee fled from the battle from fear, and thou, that wast highly thought of by them, wilt be lightly held.

In plain words: Krishna warns that the great warriors who once admired Arjuna will think he ran away out of fear. They will stop respecting him.