Sir 3:17-18, 20, 28-29
My child, conduct your affairs with humility, and you will be loved more than a giver of gifts. Humble yourself the more, the greater you are, and you will find favor with God. What is too sublime for you, seek not, into things beyond your strength, search not. The mind of a sage appreciates proverbs, and an attentive ear is the joy of the wise. Water quenches a flaming fire, and alms atone for sins.
Therein may lie a small problem, DO ALMS ATONE FOR SINS?
Of course, you've got to recognize that Sirach is an Old Testament book, so it must be included in that proper context. An example of another OT citation of this includes:
Daniel 4:24 (RSV) Therefore, O king, take my advice; atone for your sins by good deeds, and for your misdeeds by kindness to the poor; then your prosperity will be long.
As an FYI, there is also this reference:
Prov 16:6 (RSV) By loyalty and faithfulness iniquity is atoned for, and by the fear of the LORD a man avoids evil. (note: St John Chrysostom translated this, in his 9th homily on Hebrews, as “By alms-giving and acts of faithfulness sins are purged away.” He was referring to the Septuagint when making that statement -- included only as an FYI)
And then, of course, there is a famous New Testament quotation of Our Lord,
Luke 11:37-41 (RSV) While he was speaking, a Pharisee asked him to dine with him; so he went in and sat at table. The Pharisee was astonished to see that he did not first wash before dinner. And the Lord said to him, "Now you Pharisees cleanse the outside of the cup and of the dish, but inside you are full of extortion and wickedness. You fools! Did not he who made the outside make the inside also? But give for alms those things which are within; and behold, everything is clean for you.
I cite the above not to, in any way, deny the completeness or efficacy of the sacrifice of Christ on Calvary, but to point out that the quote from Sirach that you cited was not hardly unique in the Scriptures.