The stone is a foundation.
Peter when asked, believed that Christ is Lord.
On this rock I will build my foundation.
Sacrifice is the bread of life.
If any of you are to follow me, bear your own cross.
Who, if their son asks for bread, would give them a stone?
A good Father would, because a good Father would give his son a solid foundation for life. You see, bread (body) when broken can give you life but at a cost.
Man will not live on bread alone but every word that proceeds from the Father. That word is Christ. The word is a deed, least it becomes a word in vain. Thou shall take the Lord's name in vain.