Śatapatha Brāhmaṇa ("of a hundred paths") 4.5.2.3

4.5.2.3

atha vapayā caranti | yathaiva tasyai caraṇaṃ vapayā caritvādhvaryuśca yajamānaśca punaretaḥ sa āhādhvaryurnirūhaitaṃ garbhamiti taṃ ha nodarato nirūhedārtāyā vai mṛtāyā udarato nirūhanti yadā vai garbhaḥ samṛddho bhavati prajananena vai sa tarhi pratyaṅṅaiti tamapi virujya śroṇī pratyañcaṃ nirūhitavai brūyāt

They then perform with the omentum, just as its mode of performance is. Having performed with the omentum, both the Adhvaryu and Sacrificer return (to the sacrificial ground). The Adhvaryu says, 'Pull out that embryo!' otherwise he would not pull it out from the womb, since it is only pulled out from the womb of a sick or dead (female); but when the embryo is full grown, then indeed it comes out through birth: let him bid him pull it out even after tearing asunder the thighs.