Prince William will be honoring his father King Charles III, during his coronation on Saturday. William is also the heir to the throne and on Saturday’s ceremony, he will vow his loyalty and allegiance to the king during ceremony.

According to the liturgy of the service, about halfway through the historic ceremony, William will kneel before his father, place his hands between his and recite: “I, William, Prince of Wales, pledge my loyalty to you and faith and truth I will bear unto you, as your liege man of life and limb. So help me God.”

The Prince of Wales is the only member of the royal family who will honor the King in this manner during the service. He also appears as the Stole Royal as the Robe Royal is presented to the king. William will assist both Baroness Merron and the bishops in placing the robe on Charles. 

A similar vow, known as the Homage of Royal Blood, was taken by William’s late grandfather Prince Philip during Queen Elizabeth’s coronation. Phillip pledged to “liege man of life and limb” to the late queen in 1953.

As per the liturgy, there is a change in tradition when it comes to the Homage of the People. In the past, that role was performed by hereditary dukes and earls at Westminster Abbey during the coronation.

This year, Charles and Archbishop, the Most Rev. and Right Honorable Justin Welby have invited the public to participate in the homage.