Shatapatha Brahmana 8.7.1.13

8.7.1.13

tā haitā eva saṃyānyaḥ | etadvai devā ṛtavyābhirevemāṃlokāntsamayuritaścordhvānamutaścārvācastathaivaitadyajamāna ṛtavyābhirevemāṃlokāntsaṃyātītaścordhvānamutaścārvācaḥ

Now these same (bricks) are indeed steppingstones, for by means of the seasonal (bricks) the gods then stepped over these worlds, hath from hence upwards and from above downwards: and in like manner does the Sacrificer now, by means of the seasonal (bricks), step over these worlds, both from hence upwards and from above downwards.