कार्ये हि कारणं पश्येत्पश्चात्कार्यं विसर्जयेत् ।कारणत्वं स्वतो नश्येदवशिष्टं भवेन्मुनिः ॥ १३९ ॥
In plain words
Look into the effect and see the cause standing there; then let the effect go. With nothing left to cause, being-a-cause dies on its own — and the sage is what remains.
Close to the Sanskrit
In the effect, indeed, one should see the cause; afterwards one should let go of the effect. Causehood perishes of itself; the sage becomes that which remains.