Atharvaveda

AVS 6.43.2

Supported

ayáṃ yó bhū́rimūlaḥ samudrám avatíṣṭhati | darbháḥ pr̥thivyā́ útthito manyuśámana ucyate ||2||

Translation

This that is many-rooted, [that] reaches down (''ava-sthā'') to the sea, the ''darbhá'', arisen out of the earth, is called a fury-appeaser.

ShelfmarkVG:AV:SAU:K06:S043:V002cited as AVS 6.43.2

The traditional hymn heading, not a statement inside the verse.

Insufficient evidence

No other passage in this corpus carries this wording. That is a statement about the four collections held here, not about the Vedas.

How attribution was recorded1

Three rows, not four, and the shape of the answer is the point: the Samaveda carries no seer at all, while the Yajurveda's 1,960 passages are 1,960 source-stated and 0 inherited and the Atharvaveda's 5,084 are the exact reverse. So 'how many mantras have a named seer' has three different meanings in three corpora, and a single corpus-wide figure averages a per-verse attribution against a hymn label. Prefer `source_stated` for any defensible claim about a named seer.
rishi_layer_reach_by_veda