A.T. Robertson Commentary John 16:20

"Verily, verily, I say unto you, that ye shall weep and lament, but the world shall rejoice: ye shall be sorrowful, but your sorrow shall be turned into joy." — John 16:20 (ASV)

Ye shall weep and lament (κλαυσετε κα θρηνησετε). Future active of κλαιω and θρηνεω, both old words (for κλαιω see Joh 11:31, for θρηνεω see Mt 11:17), both words used of the loud lamentations so common in the east.

Shall rejoice (χαρησετα). Second future passive of χαιρω in violent contrast. Picture the women on the way to the Cross (Luke 23:27, εκοπτοντο κα εθρηνουν, two descriptive imperfects) and Mary Magdalene by the tomb (John 20:11, κλαιουσα).

Ye shall be sorrowful (λυπηθησεσθε). First future passive of λυπεω, word for inward grief. See the change from sorrow to joy in 20:14-16 when "they disbelieved for joy" (Luke 24:41). So violent was the reaction on the sudden appearance of Jesus.