A dictionary of Proverbs (Oxford Paperback Reference)

A MOUSE may help a lion
The proverb alludes to Aesop’s fable of the lion and the rat, which is told by Caxton in Fables (1484) 40.

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  1563 Mirror for Magistrates (1938) 274 The mouse may sometyme help the Lyon in nede. .. O prynces seke no foes. 1732 T. FULLER Gnomologia no. 264 A Lyon may come to be beholding to a Mouse. 1842 MARRYAT Percival Keene I. xvii. A mouse may help a lion, as the fable says. 1935 J. BUCHAN House of Four Winds xi. I only offer to show my gratitude by doing what I can. . . A mouse may help a lion. ■ assistance; great and small
  

mouse see also ONE for the mouse, one for the crow; also MICE.
mouth see out of the FULLNESS of the heart the mouth speaks; never look a GIFT horse in the mouth; GOD never sends mouths but He sends meat; a SHUT mouth catches no flies; a SOW may whistle, though it has an ill mouth for it.
Out of the MOUTHS of babes-Young children may speak disconcertingly wisely or aptly at times. The proverb is used in a variety of abbreviated and allusive forms, often without a knowledge of the complete biblical quotations (both AV): PSALMS viii. 2 Out of the mouth of babes and sucklings hath thou ordained strength; MATTHEW xxi. 16 Jesus saith unto them [the Pharisees], Yea; have ye never read, Out of the mouth of babes and sucklings thou hast perfected praise.

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  1899 R. KIPLING Stalky & Co. II In the present state of education I shouldn’t have thought any three boys would be well enough grounded. . . But out of the mouths—. 1906-Puck of Pook’s Hill 285 Out of the mouths of babes do we learn. 1979 ‘C. AIRD’ Some die Eloquent xviii. It was something Crosby said. .. ‘About the source of the
  

money.’ ‘Out of the mouths,’ conceded Leeyes. ■ children; wisdom