Charles H. Spurgeon on Psalms 135:19

Bless the LORD, O house of Israel. All of you, in all your tribes, praise the one Jehovah. Each tribe, from Reuben to Benjamin, has its own special cause for blessing the Lord, and the nation as a whole has substantial reasons for pouring out benedictions upon his name. Those whom God has named "the house of Israel", a family of prevailing princes, ought to show their loyalty by thankfully bowing before their sovereign Lord. Bless the LORD, O house of Aaron. These were elected to high office and permitted to draw very near to the divine presence; therefore they beyond all others were bound to bless the Lord. Those who are favoured to be leaders in the church should be foremost in adoration. In God's house the house of Aaron should feel bound to speak well of his name before all the house of Israel.