The very stone which the builders rejected...

"But when the tenants saw the son, they said to themselves, 'This is the heir; come, let us kill him and have his inheritance.'
And they took him and cast him out of the vineyard, and killed him.
When therefore the owner of the vineyard comes, what will he do to those tenants?"

They said to him, "He will put those wretches to a miserable death, and let out the vineyard to other tenants who will give him the fruits in their seasons."

Jesus said to them, "Have you never read in the scriptures:
'The very stone which the builders rejected
has become the head of the corner;
this was the Lord's doing, and it is marvelous in our eyes'?

Therefore, I tell you, the kingdom of God will be taken away from you and given to a nation producing the fruits of it."
(Matt 21:38-43)

We always need to humbly ask what is God's doing behind what appears to be.
As long as we keep this humility of continuing communication/conversation with God, that would (or at least might) allow God to work through us.