Also see definition of "Comfortably" in Word Study
Study Dictionary
Comfortably
COMFORTABLY [ISBE]
COMFORTABLY - kum'-fer-ta-bli (`al lebh, "to the heart"): "To speak to the heart," i.e. to speak kindly, to console, to comfort, is the ordinary Hebrew expression for wooing: e.g. Boaz spake "to the heart" of Ruth (Ruth 2:13 margin; the King James Version "friendly," the Revised Version (British and American) "kindly"). The beauty of the Hebrew term is illustrated in Gen 50:21 where Joseph "spake kindly" unto his brethren, winning them from fear to confidence. Rendered "comfortably" in five passages: thrice of human speaking, and twice of the tenderness of God's address to His people. David was urged to win back the hearts of the people by kind words: "speak comfortably" (2 Sam 19:7). Hezekiah in like manner comforted the Levites (2 Ch 30:22) and encouraged his captains (2 Ch 32:6). The term has exceptional wealth of meaning in connection with God's message of grace and forgiveness to His redeemed people. The compassionate love that has atoned for their sins speaks to the heart ("comfortably") of Jerusalem, saying "that her iniquity is pardoned" (Isa 40:2). The same promise of forgiveness is given to the penitent nation by the prophet Hosea (Hos 2:14); "comfortable words" (Zec 1:13), i.e. words affording comfort.Dwight M. Pratt
Also see definition of "Comfortably" in Word Study