The Maitrayaniya Upanishad is an ancient Sanskrit text that is embedded inside the Yajurveda. It is also known as the Maitri Upanishad, and is listed as number 24 in the Muktika canon of 108 Upanishad
A page of the Maitrayaniya Upanishad manuscript found in Pune, Maharashtra (Sanskrit, Devanagari)
Vajrasuchi Upanishad sample i, Samaveda, Sanskrit, Devanagari script, 1728 CE manuscript