Rabbi Chiya says that when the sun begins to set, the energy of the sun, Zeir Anpin, is less powerful, and that is when the left dominates and judgments pertain. At that time one must pray.
1. "And Hashem spoke to Moses, saying, 'Send you men, that they may spy out the land of Canaan...'" (Bemidbar 13:1). Rabbi Chiya opened the discussion saying, "Have you commanded the morning since your days began; and caused dayspring to know its place" (Iyov 38:12). It is written "dayspring" WITHOUT THE HEI (DEFINITE ARTICLE). Hei has been far from dawn. What is the reason? Rabbi Chiya said: When the evening shadows lengthen and the sun - THAT IS, ZEIR ANPIN - begins to set, MEANING AFTER MIDDAY, the strength OF THE SUN is less powerful, WHICH IS ZEIR ANPIN. This is when the left rules and Judgment prevails and spreads over the world. Then a person is required to pray and direct his desire to his Master.