Verse 3: And they said, If ye send away the ark of the God of Israel, send it not (Ex. 23:15; Deut. 16:16) empty; but in any wise return him (Lev. 5:15, 16) a trespass offering: then ye shall be healed, and it shall (1 Sam. 6:9) be known to you why his hand is not removed from you.
[If ye send back] They do not say, send ye back. 1. Because the best counselors give answers only to things asked. But the Philistines had asked, not whether they ought to send the Ark back (for this was determined in the preceding chapter [Mendoza on verse 2]), but in what manner they ought to send it back. 2. It was not necessary to advise the Philistines to send the Ark back, having already been stirred up to that by their own will (Mendoza). If ye send back, that is, ye decide to send back (Vatablus in the Tigurinus Notes). What things are going to happen with certainty are said to be done already; or certainly, the act itself is used in the place of the intention to act (Mendoza).
[Do not send it back empty, רֵיקָם] Being empty of gifts (Junius and Tremellius). Hebrew: emptily (Drusius, Junius and Tremellius, Piscator). It is Heterosis (Piscator). It has an adverbial form (like חִנָּם/freely/graciously, and אָמְנָם/truly [Drusius]), that is, without gifts (Vatablus, Drusius, Malvenda). Perhaps they learned that from the Jews, nearby and subject to them, Exodus 23:15, thou shalt not appear…empty (Sanchez). Evidently, according to the opinion of idolaters, Gifts, believe me, placate men and gods. Which is thus set down in Homer, Δῶρα Θεοὺς πείθει, δῶρ᾽ αἰδοίους βασιλῆας, gifts persuade the gods and august kings, Plato reprehends in Concerning the Republic 3 (Grotius). It is the sense of all nations, that they esteem God to be honored by oblations (Menochius).
Empty, that is, without a present; which they judged necessary, from the common opinion and practice both of Jews and Gentiles.
[But what ye owe for sin, render to Him, כִּֽי־הָשֵׁ֥ב תָּשִׁ֛יבוּ ל֖וֹ אָשָׁ֑ם] But in rendering render (altogether render [Tigurinus, Junius and Tremellius]) an oblation (Munster). A sacrifice for sin or trespass (Pagnine, Drusius). A culpatory (Montanus). An oblation of expiation (Jonathan); gifts (Syriac, similarly the Arabic); guilt (Junius and Tremellius), that is, an oblation for guilt, as in Leviticus 5:4 and elsewhere: that is to say, we do not see the sin: but it can be that ye are guilty because of something omitted from His rites (Malvenda and Piscator out of Junius). Discharge what ye owe to Him; namely, an oblation for sin, inasmuch as ye took the Ark (Vatablus). They owed both internal contrition and external oblation: Concerning the former they cared not, but only concerning the latter, cleaving to their idolatry. Men render to God external gifts more readily than internal gifts (Mendoza). הָשֵׁב signifies to return and to restore; inasmuch as man sinning, insofar as he is able, takes that which belongs to God, and usurps it to himself; and so he is obliged to return again the thing taken, if he wishes to have God propitious towards him (Munster out of the Hebrews). That restitution is contrition of the heart; and the external oblation is a sign of this (Munster). To God we are able, not so much to give, and to return: since we return only what we have received from Him (Mendoza).
Return him a trespass-offering; thereby to acknowledge our offence, and obtain his pardon.
[Then ye shall be healed, and shall know why His hand is not removed from you (similarly the Syriac, Munster, Pagnine, Tigurinus, Montanus, Piscator)] That is, Why He does not cease to afflict you (Vatablus). Ye shall know the origin of this punishment upon you. For, if it be of some other cause, it will continue after the restoration of the Ark (Mendoza). [Others translate ו/and by or:] Either ye shall be healed, or it shall be known to you, why His hand is not removed, etc. (Junius and Tremellius, Drusius), that is, He is not the reason why this plague does not cease from you: but it is an accident, as in 1 Samuel 6:9 (Malvenda out of Junius). But I prefer to retain the and. The second clause is a corollary from the first, in this manner: if we will recover our health through oblation, then the hand of God did not cease from smiting use because of the neglect of that oblation (Piscator). For seven months they were most grievously afflicted; and yet, as they were in a stupor of mind, they were not clearly understanding who was the author of the plagues, and what was the cause of them (Menochius).
[אָז תֵּרָֽפְאוּ֙ וְנוֹדַ֣ע לָכֶ֔ם לָ֛מָּה לֹא־תָס֥וּר יָד֖וֹ מִכֶּֽם׃] [Others translate it thus:] And then ye shall be healed, and it shall be rendered favorable to us (or, and there shall be rest for us [Jonathan]). Shall not His hand cease from us? (Septuagint). Or, why shall not His smiting cease from us? (Jonathan). And the sentence appears sufficiently suitable (Nobilius).
It shall be known to you; you shall understand what is hitherto doubtful, whether he was the author of these calamities, and why they continued so long upon you. Compare 1 Samuel 6:7-9.
 Hebrew: וַיֹּאמְר֗וּ אִֽם־מְשַׁלְּחִ֞ים אֶת־אֲר֙וֹן אֱלֹהֵ֤י יִשְׂרָאֵל֙ אַל־תְּשַׁלְּח֤וּ אֹתוֹ֙ רֵיקָ֔ם כִּֽי־הָשֵׁ֥ב תָּשִׁ֛יבוּ ל֖וֹ אָשָׁ֑ם אָ֤ז תֵּרָֽפְאוּ֙ וְנוֹדַ֣ע לָכֶ֔ם לָ֛מָּה לֹא־תָס֥וּר יָד֖וֹ מִכֶּֽם׃  That is, a hybrid.  Exodus 23:15: “Thou shalt keep the feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty [רֵיקָם]:)…”  Ovid’s De Arte Amandi 3. אָשָׁם/offence/trespass/trespass-offering is related to the verb אָשַׁם, to offend or be guilty.  Leviticus 5:4-6: “Or if a soul swear, pronouncing with his lips to do evil, or to do good, whatsoever it be that a man shall pronounce with an oath, and it be hid from him; when he knoweth of it, then he shall be guilty (וְאָשֵׁם) in one of these. And it shall be, when he shall be guilty (כִי־יֶאְשַׁם) in one of these things, that he shall confess that he hath sinned in that thing: and he shall bring his trespass offering (אֶת־אֲשָׁמוֹ) unto the Lord for his sin which he hath sinned, a female from the flock, a lamb or a kid of the goats, for a sin offering; and the priest shall make an atonement for him concerning his sin.”  Hebrew: אָז תֵּרָֽפְאוּ֙ וְנוֹדַ֣ע לָכֶ֔ם לָ֛מָּה לֹא־תָס֥וּר יָד֖וֹ מִכֶּֽם׃.