Commentary on the Bible, by Adam Clarke, [1831], at sacred-texts.com
The psalmist professes his humility, and the peaceableness of his disposition and conduct, Psa 131:1, Psa 131:2. Exhorts Israel to hope in God, Psa 131:3.
Some think that David composed this Psalm as a vindication of himself, when accused by Saul's courtiers that he affected the crown, and was laying schemes and plots to possess himself of it. Others think the Psalm was made during the captivity, and that it contains a fair account of the manner in which the captives behaved themselves, under the domination of their oppressors.
Lord, my heart is not haughty - The principle of pride has no place in my heart; and consequently the high, lofty, and supercilious look does not appear in my eyes. I neither look up, with desire to obtain, to the state of others, nor look down with contempt to the meanness or poverty of those below me. And the whole of my conduct proves this; for I have not exercised myself - walked, in high matters, nor associated myself with the higher ranks of the community, nor in great matters, נפלאות niphlaoth, wonderful or sublime things; too high for me, ממני mimmeni, alien from me, and that do not belong to a person in my sphere and situation in life.
I have behaved and quieted myself, as a child - On the contrary, I have been under the rod of others, and when chastised have not complained; and my silence under my affliction was the fullest proof that I neither murmured nor repined, but received all as coming from the hands of a just God.
My soul is even as a weaned child - I felt I must forego many conveniences and comforts which I once enjoyed; and these I gave up without repining or demurring.
Let Israel hope in the Lord - Act all as I have done; trust in him who is the God of justice and compassion; and, after you have suffered awhile, he will make bare his arm and deliver you. Short as it is, this is a most instructive Psalm. He who acts as the psalmist did, is never likely to come to mischief, or do any to others.