Why is a little with Tzedakah better than much grain without Mishpat?
R. Yonah #1: This is connected to verse 9 - "Lev Adam Yechashev Darko va'Shem Yachin Tza'ado." Man should arouse his heart to know to know and see that there is great evil in every sin that he does. This is a rebuke to those who gather great harvests against Mishpat. Man's Nefesh desires theft and covets it (Chagigah 11b).
R. Yonah #2: This refers to a Ba'al Teshuvah mentioned above - "b'Chesed ve'Emes Yechupar Avon" (6). One should not be concerned for his gold and silver to refrain from returning theft to the victim. It is better that little remain with him, and it is with Tzedakah, than much grain without Mishpat.
Malbim: This is like "Tov Me'at la'Tzadik me'Hamon Resha'im Rabim; Ki Zero'os Resha'im Tishavarnah v'Somech Tzadikim Hashem" (Tehilim 37:16-17). Hashem supports the little of the Tzadik, and Hashgachah destroys the great amount of the Rasha. The same applies to his money and property. The little that he attained with virtue, Hashem's Hashgachah is on it, and it lasts. Great harvests attained unjustly, Hashem will destroy them. This is unlike "a little with Yir'as Hashem is better than a great tumultuous storehouse" (below, 15:16). There it discusses the pleasure that he gets from it. The little that he gathers with Yir'as Hashem, he has contentment from it. Even though "Yemei Oni Ra'im" (15:15), still, this little is better than the great storehouse of "Tov Lev Mishteh Samid" (ibid). He will find tumult in it; there is no Shalom for Resha'im (Yeshayah 48:22).