Deuteronomy 15:9 Beware that there be not a thought in thy wicked heart, saying, The seventh year, the year of release, is at hand; and thine eye be evil against thy poor brother, and thou givest him nought;
Deuteronomy 19:12 Then the elders of his city shall send and fetch him thence, and deliver him into the hand of the avenger of blood, that he may die.
13 Thine eye shall not pity him,...
Luke 11:34 The light of the body is the eye: therefore when thine eye is single, thy whole body also is full of light; but when thine eye is evil, thy body also is full of darkness.
An 'evil eye' points to not pitying (showing mercy). A single eye would be the opposite (showing mercy). It's all related to the gospel. A single eye identifies with light. An evil eye with darkness.
Luke 11:34 speaks of a time (when) the eye of the body (of Christ) is full of light; and of a time (when) the eye of the body (of Christ) is evil or full of darkness.
Another way of saying it, would be a time for the Day of Salvation; and a time for the Day of Judgment.