Halakha Mazmur 17:15: Mishneh Torah, Gifts to the Poor, Kitzur Shulchan Arukh & Shulchan Arukh, Yoreh De'ah

The greatest among the sages used to give a perutah to the poor before every prayer service and only afterwards would they pray, as it is said, (Psalms 17:15) Then I, justified [betzedek], will behold Your face.¹⁹²See Babylonian Talmud Bava Batra 10a.

It is good to give charity before praying, as it is said: "As for me, with righteousness I will behold Your Presence."²Psalms 17:15. The word בְּצֶדֶק is similar to צְדָקָה, charity. You should also resolve before each prayer to fulfill the mitzvah to "Love your neighbor as yourself."³Leviticus 19:18. You must determine to love every Jew as yourself, because if there is, God forbid, dissension within Israel in this world, there is no harmony in the world above. However, when there is unity in this world it causes spiritual unity of our souls in the world above, and as a result, our prayers are unified; and when our prayers are unified, they are accepted favorably before Him, Blessed is His Name.

It is well to give a coin to some poor man before every prayer, as it is written, "As for me, I will behold thy face in righteousness" [or, "… with charity"].¹Psalms 17:15.