Śatapatha Brāhmaṇa ("of a hundred paths") 10.2.1.4

10.2.1.4

sa caturaṅgulamevobhayato'ntarata upasamūhati caturaṅgulamubhayato bāhyato vyudūhati tadyāvadevopasamūhati tāvadvyudūhati tannāhaivātirecayati no kanīyaḥ karoti tathā pucasya tathottarasya pakṣasya

He contracts (the right wing) inside on both sides by just four finger-breadths, and expands it outside on both sides by four finger-breadths: he thus expands it by just as much as he contracts it; and thus, indeed, he neither exceeds (its proper size) nor does he make it too small. In the same way in regard to the tail, and in the same way in regard to the left wing.