A.T. Robertson Commentary Matthew 18:19

"Again I say unto you, that if two of you shall agree on earth as touching anything that they shall ask, it shall be done for them of my Father who is in heaven." — Matthew 18:19 (ASV)

Shall agree (συμφωνησωσιν). Our word "symphony" is this very root. It is no longer looked at as a concord of voices, a chorus in harmony, though that would be very appropriate in a church meeting rather than the rasping discord sometimes heard even between two brethren or sisters.

Of my Father (παρα του πατρος μου). From the side of, "by my Father."