John 11:9-10

The Jews and the Romans commonly regarded the daylight hours as 12 and the nighttime hours as the other 12. Literally Jesus was referring to the daylight hours. Metaphorically the daylight hours represented the Father’s will. Jesus was safe as long as He did the Father’s will. For the disciples, as long as they continued to follow Jesus, the Light of the World, they would not stumble. Walking in the night pictures behaving without divine illumination or authorization. Living in the realm of darkness (i.e., evil) is dangerous (cf. 1 John 1:6).

"When there is darkness in the soul, then we will stumble indeed." [Note: Morris, p. 481.]