The Pali suttas of Buddhism only mention the Four Vedas as sacred Brahmin texts; giving the impression of both predating the Upanishad period.
In the Pali suttas of Buddhism, there is an account of a Brahmin guru named Bāvari (in the locality of Assaka, near to Mūḷaka, close to the bank of the Godhāvarī River) who sends out his disciples to speak to the Buddha Gotama. One of the Brahmin Bāvari's disciples named Tissa Metteyya is said to have asked Buddha Gotama the following question (per the Pali text):
Kassa no santi iñjitā;Ko ubhantamabhiññāya, Majjhe mantā na lippati; Kaṃ brūsi mahāpurisoti, Ko idha sibbinimaccagā
Who is the wise man, who has known both ends, and is undefiled in the middle? Who do you say is a Great Man? Who has gone beyond the seamstress (sibbini) here?”
In the Vedas or, otherwise, Upanishads, is there any account of these persons (Brahmin Bāvari; Tissa Metteyya; etc) and, in particular, the notion/concept of "The Seamstress"?