Revelation 1:10
On
ἐν (en)
Preposition
Strong's 1722: In, on, among. A primary preposition denoting position, and instrumentality, i.e. A relation of rest; 'in, ' at, on, by, etc.
the
τῇ (tē)
Article - Dative Feminine Singular
Strong's 3588: The, the definite article. Including the...