וַיֹּאמְר֗וּ אִֽם־מְשַׁלְּחִ֞ים אֶת־אֲר֨וֹן אֱלֹהֵ֤י יִשְׂרָאֵל֙ אַל־תְּשַׁלְּח֤וּ אֹתוֹ֙ רֵיקָ֔ם כִּֽי־הָשֵׁ֥ב תָּשִׁ֛יבוּ ל֖וֹ אָשָׁ֑ם אָ֤ז תֵּרָֽפְאוּ֙ וְנוֹדַ֣ע לָכֶ֔ם לָ֛מָּה לֹא־תָס֥וּר יָד֖וֹ מִכֶּֽם׃
And they said: ‘If ye send away the ark of the God of Israel, send it not empty; but in any wise return Him a guilt-offering; then ye shall be healed, and it shall be known to you why His hand is not removed from you.’
Rashi
If his soul makes itself restitution, etc. Said the Holy One, blessed be He, “I will see, if his soul will be given and delivered with My holiness to return it to Me as restitution for all that he betrayed Me, I will pay him his recompense, and he will see children, etc.” This word אָשָׁם is an expression of ransom that one gives to the one against when he sinned, amende in O.F., to free from faults, similar to the matter mentioned in the episode of the Philistines (I Sam. 6:3), “Do not send it away empty, but you shall send back with it a guilt offering (אָשָׁם).”