Śatapatha Brāhmaṇa ("of a hundred paths") 5.3.5.30

5.3.5.30

tāḥ prayacati | pātainam prāñcam pātainam pratyañcam pātainaṃ tiryañcaṃ digbhyaḥ pāteti tadasmai sarvā eva diśo 'śaravyāḥ karoti tadyadasmai dhanuḥ prayacati vīryaṃ vā etadrājanyasya yaddhanurvīryavantamabhiṣiñcānīti tasmādvā asmā āyudham prayacati

These he hands to him with, 'Protect ye him in front!--Protect ye him from behind!--Protect ye him from the side!--Protect ye him from (all) quarters!' Thus he makes all the quarters safe from arrows for him. And as to why he hands the bow to him;--this, the bow, truly is the nobleman's strength: it is because he thinks, 'I will consecrate him when endowed with strength!' that he hands the weapon to him.