Jesus knew that the Father had put all things under his power, and that he had come from God and was returning to God; so he got up from the meal, took off his outer clothing, and wrapped a towel round his waist. After that, he poured water into a basin and began to wash his disciples’ feet, drying them with the towel that was wrapped round him. He came to Simon Peter, who said to him, “Lord, are you going to wash my feet?”
Jesus replied, “You do not realise now what I am doing, but later you will understand.”
“No,” said Peter, “you shall never wash my feet.” Jesus answered, “Unless I wash you, you have no part with me.”
“Then, Lord,” Simon Peter replied, “not just my feet but my hands and my head as well!”
Jesus answered, “A person who has had a bath needs only to wash his feet; his whole body is clean. And you are clean, though not every one of you.” Jn 13:1-10

Whilst Peter didn’t get it straight away…

Young men, in the same way be submissive to those who are older. All of you, clothe yourselves with humility towards one another, because, “God opposes the proud but gives grace to the humble.” Humble yourselves, therefore, under God’s mighty hand, that he may lift you up in due time. 1 Pe 5:5-6

…he eventually understood what was going on.