What does 2 Samuel 15:33 mean?

David went up by the ascent of the Mount of Olives, and wept as he went up; and he had his head covered, and went barefoot: and all the people who were with him each covered his head, and they went up, weeping as they went up.

Someone told David, saying, “Ahithophel is among the conspirators with Absalom.” David said, “Yahweh, please turn the counsel of Ahithophel into foolishness.”

When David had come to the top, where God was worshiped, behold, Hushai the Archite came to meet him with his coat torn, and earth on his head.

but if you return to the city, and tell Absalom, ‘I will be your servant, O king. As I have been your father’s servant in time past, so will I now be your servant; then will you defeat for me the counsel of Ahithophel.’

Don’t you have Zadok and Abiathar the priests there with you? Therefore whatever you hear out of the king’s house, tell it to Zadok and Abiathar the priests.

Behold, they have there with them their two sons, Ahimaaz, Zadok’s son, and Jonathan, Abiathar’s son. Send to me everything that you shall hear by them.”