2 Samuel 17:17-18

17Now Jonathan and Ahimaaz [the priests’ sons] were staying at En-rogel, and a maidservant [appearing to go for water] would go and tell them [what was happening], and they would go [secretly] and inform King David; for they could not [allow themselves to] be seen coming into the city [of Jerusalem].

18But a boy saw them and told Absalom; so the two of them left quickly and came to the house of a man in Bahurim, who had a well in his courtyard, and [with his permission] they went down into it.