After He (Jesus) said these things He spit on the ground, made some mud from the saliva, and spread the mud on his eyes. “Go,” He told him, “wash in the pool of Siloam” (which means “Sent”). So he left, washed, and came back seeing. - John 9:6-7
Jesus put spit and dirt in the blind man’s eyes! We know that Jesus healed others with just a word or a touch. In fact, Jesus healed some, like the Roman centurion’s servant, who’s physical location was many miles away (Luke 7:1-10). Why use mud?