páśyati from Proto-Indo-Aryan *(s)páśyati, from Proto-Indo-Iranian *spáćyati, from Proto-Indo-European *spéḱyeti, present form of *speḱ-

spaṣṭá  from Proto-Indo-Aryan *spaṣṭás, from Proto-Indo-Iranian *spaštás, from Proto-Indo-European *spₔḱ-tós, from *speḱ- 'to see'

Pokorny, Julius (1959 Indogermanisches etymologisches Wörterbuch, volume 3, Bern, München: Francke Verlag, page 984
Rix, Helmut, editor (2001) Lexikon der indogermanischen Verben, 2nd edition, Wiesbaden: Dr. Ludwig Reichert Verlag, pages 575-576
De Vaan, Michiel (2008), Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill, pages 578-579
Beekes, Robert S. P. (2010) Etymological Dictionary of Greek (Leiden Indo-European Etymological Dictionary Series; 10), volume II, with the assistance of Lucien van Beek, Leiden, Boston: Brill, pages 1347-1348
Cheung, Johnny (2007), Etymological Dictionary of the Iranian Verb (Leiden Indo-European Etymological Dictionary Series; 2), Leiden, Boston: Brill, pages 353-354

Ringe, Donald (2006) From Proto-Indo-European to Proto-Germanic (A Linguistic History of English; 1)‎, Oxford: Oxford University Press