Psalm 131 begins with an assertion of humility, "O Lord, my heart is not proud nor my look haughty; I do not aspire to great things or to what is beyond me." I'm pausing here to ponder how honestly a typical modern can pray this psalm. Don't we think a heart should be proud? Is it hard for us to admit that some things are beyond us? How willing are we to limit our aspirations? Or, I'm wondering if we, on the other hand, can pray this psalm quite honestly. Our humility is part of what drives us to our places of worship. Of course, we can't do everything. Of course, we don't understand why some things turn out the way they do. But, I'm still having trouble with the not-occupying myself part. I, at least, if not we, do tend to worry about a lot of things.
Back to the psalm.
The words of the psalm link the one on the way to the Temple (or on the way home from exile, or the one seeking the presence of God) to a small child with its mother. From an assertion of humility to an example of it. It's hard to come up with a relationship in which one party provides for the needs of the other--even when that other isn't behaving particularly well at all--than the mother and her child.
Sideline: Psalms 120 through 134 all begin with the superscription, "A song for ascents." According to the notes in the Jerusalem Study Bible, there are several theories about the designation "ascents," the English translation for "ma'alah." Among these theories are the early rabbinic tradition that deduced that there 15 of these psalms to match the 15 steps of the Temple (see Ezekiel 40:26, 31). Some modern scholars connect these psalms to the return from exile. Others have a allegorist understanding; that is, the ascent is of the individual to God.