Charles H. Spurgeon on Psalms 136:19

Sihon king of the Amorites. Let the name be mentioned that the mercy may be the better remembered. Sihon smote Moab, but he could not smite Israel, for the Lord smote him. He was valiant and powerful, so as to be both great and famous; but as he wilfully refused to give a peaceful passage to the Israelites, and fought against them in malice, there was no choice for it but to let him run into that destruction which he courted. His fall was speedy and final, and the chosen people were so struck with it that they sung of his overthrow in their national songs. For his mercy endureth for ever. His mercy is no respecter of persons, and neither the greatness nor the fame of Sihon could protect him after he had dared to attack Israel. The Lord will not forsake his people because Sihon blusters.

Come what may

By night or day,

Still most sure,

His love shall dure.