Yonder hills are inaccessible. O hero, save the passage obtained by the practice of asceticism, there is no passage to that place. This is the path of the celestials; it is ever impassable by mortals. Out of kindness, O hero, do I dissuade thee. Do thou hearken unto my words. Thou canst not proceed further from this place. Therefore, O lord, do thou desist. O chief of men, to-day in very way thou art welcome to this place.

In plain words: Hanuman warns that the mountains ahead are the path of the gods. Ordinary people cannot pass, except through long spiritual discipline. He says he is stopping Bhima out of kindness and welcomes him to stay.