The words of Psalm 131 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.
Background: 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 are 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.