What evidence is in the Bible to say sickness is a blessing?
Sickness teaches us to always remember to show compassion on others, especially those of the household of faith.
Matthew 25:35-36,39-40,43-45 KJV
For I was an hungred, and ye gave me meat: I was thirsty, and ye gave me drink: I was a stranger, and ye took me in:
[36] Naked, and ye clothed me: I was sick, and ye visited me: I was in prison, and ye came unto me.
[39] Or when saw we thee sick, or in prison, and came unto thee?
[40] And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
[43] I was a stranger, and ye took me not in: naked, and ye clothed me not: sick, and in prison, and ye visited me not.
[44] Then shall they also answer him, saying, Lord, when saw we thee an hungred, or athirst, or a stranger, or naked, or sick, or in prison, and did not minister unto thee?
[45] Then shall he answer them, saying, Verily I say unto you, Inasmuch as ye did it not to one of the least of these, ye did it not to me.