A.T. Robertson Commentary Matthew 10:13

"And if the house be worthy, let your peace come upon it: but if it be not worthy, let your peace return to you." — Matthew 10:13 (ASV)

If the house be worthy (εαν η η οικια αξια). Third class condition. What makes a house worthy? "It would naturally be readiness to receive the preachers and their message" (McNeile). Hospitality is one of the noblest graces and preachers receive their share of it. The apostles are not to be burdensome as guests.