Śatapatha Brāhmaṇa ("of a hundred paths") 3.9.4.23

3.9.4.23

atha yasmādyajño nāma | ghnanti vā enametadyadabhiṣuṇvanti tadyadenaṃ janayanti sa tāyamāno jāyate sa yanjāyate tasmādyañjo yañjo havai nāmaitadyadyajña iti

Then as to why he is called Yagña (sacrifice). Now, when they press him, they slay him; and when they spread him, they cause him to be born. He is born in being spread along, he is born moving (yan gâyate): hence yan-ga, for 'yañga' they say, is the same as 'yagña.'