देवताद्वन्द्वे च

Thus इन्द्रावरुणौ, इन्द्रासोमौ, इन्द्राबृहस्पती, मित्रावरुणौ ॥ The repetition of the word Dvandva in this sutra, in spite of its anuvritti from the last, shows that the rule applies only to such Dvandvas which are generally found in the Vedas and are well-known. It does not apply to compounds like ब्रह्मप्रजापति, शिववैश्रवणौ ॥ In fact it applies to the Dvandva of those Devatas whose companionship is well-known.

Vart:- Prohibition must be stated with regard to वायु in both cases, whether first or last, as अग्निवायू or वाय्वग्नी ॥,