What is meant by "the two sacrificed ones" in the Prophet's saying, "I am the son of the two sacrificed ones"?

The two sacrifices are: Ishmael, peace be upon him, whom Allah ransomed with a great sacrifice, and Abdullah, the father of the Prophet, may Allah bless him and grant him peace, who was saved from being sacrificed after his father, Abdul-Muttalib, vowed to sacrifice him at the Kaaba and ransomed him with one hundred camels. The Prophet, may Allah bless him and grant him peace, was asked about the two sacrifices, and he smiled and informed them of this.