O demigods, fulfilling one’s own interests is so important that one may even have to make a truce with one’s enemies. For the sake of one’s self-interest, one has to act according to the logic of the snake and the mouse.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
अरयोऽपि हि सन्धेयाः सति कार्यार्थगौरवे । अहिमूषिकवद्देवा ह्यर्थस्य पदवीं गतैः
arayo'pi hi sandheyāḥ sati kāryārthagaurave | ahimūṣikavaddevā hyarthasya padavīṃ gataiḥ
SB 8.6.20