Albert Barnes Commentary John 9:6

"When he had thus spoken, he spat on the ground, and made clay of the spittle, and anointed his eyes with the clay," — John 9:6 (ASV)

And made clay, etc. Two reasons may be assigned for making this clay and anointing the eyes with it. One is that the Jews regarded spittle as medicinal for diseased eyes, and that they forbade the use of medicines on the Sabbath. They regarded the Sabbath so strictly that they considered the preparation and use of medicines as contrary to the law.

Especially, it was particularly forbidden among them to use spittle on that day to heal diseased eyes. (See instances in Lightfoot.) Jesus, therefore, by making this spittle, showed them that their manner of keeping the day was superstitious, and that He dared to do a thing which they considered unlawful.

He showed that their interpretation of the law of the Sabbath was contrary to the intention of God, and that His disciples were not bound by their notions of the sacredness of that day. Another reason may have been that it was common for prophets to use some symbolic or expressive action when performing miracles. Thus Elisha commanded his staff to be laid on the face of the child that he was about to restore to life (2 Kings 4:29). (See Barnes on Isaiah 8:18).

In such instances, the prophet showed that the miracle was performed by power communicated through him; so, in this case, Jesus by this act showed the blind man that the power of healing came from Him who anointed his eyes. He could not see Him, and the act of anointing convinced him of what might have been known without such an act, could he have seen Him—that Jesus had power to give sight to the blind.