Charles H. Spurgeon on Psalms 40:16

Let such as love thy salvation say continually, The Lord be magnified. Jesus who gave us our capacity of happiness and our capacity of speaking, realised the relation which he had established between them; and hence in praying for his friends, he prayed that in the joy and gladness of their souls they might say, "The Lord be magnified." He desired them to speak of their holy happiness; and it was his wish that when they did speak of it they should speak in terms of praise of Jehovah, for he was the source of it. He desired them to say continually, The Lord be magnified. James Frame.