कारणं व्यतिरेकेण पुमानादौ विलोकयेत् ।अन्वयेन पुनस्तद्धि कार्ये नित्यं प्रपश्यति ॥ १३८ ॥
In plain words
First, by vyatireka — exclusion — set the effect aside and look at the cause alone. Then, by anvaya — co-presence — see that same cause, always, right there in the effect.
Close to the Sanskrit
The cause, by exclusion (vyatireka), the person should behold at first; then by inherence (anvaya) he sees that very cause always in the effect.