A friend in need is a friend indeed

आपत्काले तु सम्प्राप्ते
यन्मित्रं मित्रमेव तत् ।
वृद्धिकाले तु सम्प्राप्ते
दुर्जनोऽपि सुहृद्भवेत् ॥

- पञ्चतन्त्रम्

Whoever is friendly in adversity, is indeed a true friend. In prosperity, even a wicked person wants to be a friend.

A friend in need is a friend indeed.
It is prosperity that gives us friends, adversity that proves them.