Wherefore should the heathen say, Where is their God? let him be known among the heathen in our sight by the revenging of the blood of thy servants which is shed.
Wherefore should the heathen say, Where is their God? The Psalmist here has in mind Deuteronomy 32:12; especially Joel 2:17, which is here repeated verbatim - i:e., What has become of His much-celebrated omnipotence and unfailing love to His people? (Deuteronomy 9:28.)
Let him be known among the heathen in our sight (by) the revenging of the blood of thy servants which is shed - rather 'let there be known among the pagan in our sight (Deuteronomy 6:22) the revenging of the blood of thy servants which is shed.' The Psalmist has in mind Deuteronomy 32:43.