Shiva Purana
रजो गात्रोर्ध्वबाहू च सवनश्चानयश्च यः ॥ सुतपाश्शुक्र इत्येते सप्त सप्तर्षयः स्मृताः ॥ ३४ ॥
The dust of the body, the upper arms, the sacrificial fire and the others. The seven sages are known as Sutapā and Śukra.
english translation
rajo gAtrordhvabAhU ca savanazcAnayazca yaH ॥ sutapAzzukra ityete sapta saptarSayaH smRtAH ॥ 34 ॥
hk transliteration by Sanscript