Adam Clarke on Psalms 66:16

Come and hear, all ye that fear God - While in captivity, the psalmist had sought the Lord with frequent prayer for his own personal salvation, and for the deliverance of the people; and God blessed him, heard his prayer, and turned the captivity. Now that he is returned in safety, he is determined to perform his vows to the Lord; and calls on all them that fear their Maker, who have any religious reverence for him, to attend to his account of the Lord's gracious dealings with him. He proposes to tell them his spiritual experience, what he needed, what he earnestly prayed for, and what God has done for him. Thus he intended to teach them by example, more powerful always than precept, however weighty in itself, and impressively delivered.