night.. Homonym. Hebrew. nesheph = darkness, here, but daylight in Job 7:4; 1 Samuel 30:17. See notes there. The Revised Version, in doubt, renders it here "twilight".
pleasure. joy.
fear. trembling.
Related Commentaries of Isaiah 21:4
Isaiah 21:4
4 My heartb panted, fearfulness affrighted me: the night of my pleasure hath he turned into fear unto me.