I’m just curious is there actual scripture that says what the number 3 and 7 mean? Or is this something people just assume and are adding there own thoughts or interpretation. If it wasn’t explained or clearly said couldn’t they just be reoccurring numbers that weren’t meant to have real significance? I really have no idea. I’m just curious where the certainty comes from about the meanings of these numbers. Thanks for any response.
The number 7 can be backed with the strongest evidence from Scripture as meaning fullness, completion. For instance...
Matthew 18:21-22:
Then Peter came to Jesus and asked, “Lord, how many times shall I forgive my brother or sister who sins against me? Up to seven times?”
Jesus answered, “I tell you, not seven times, but seventy-seven times.
Hebrews 4:4-11:
For somewhere he has spoken about the seventh day in these words: “On the seventh day God rested from all his works.” And again in the passage above he says, “They shall never enter my rest.”
Therefore since it still remains for some to enter that rest, and since those who formerly had the good news proclaimed to them did not go in because of their disobedience, God again set a certain day, calling it “Today.” This he did when a long time later he spoke through David, as in the passage already quoted:
“Today, if you hear his voice,
do not harden your hearts.”
For if Joshua had given them rest, God would not have spoken later about another day. There remains, then, a Sabbath-rest for the people of God; for anyone who enters God’s rest also rests from their works just as God did from his. Let us, therefore, make every effort to enter that rest, so that no one will perish by following their example of disobedience.
I think you can follow this without explanation, however , if you need some explanation let me know.
The proof of the number three representing God's purpose is just another observation of its usage. The fact that one can't quite explain why Jesus said He'd be in the grave three nights and three days but doesn't seem to quite be, maybe...only maybe...can be explained by what seems a common usage of 3 for purpose.