5 Heb “one who slaughters a bull, one who strikes down a man.” Some understand a comparison here and in the following lines. In God’s sight the one who sacrifices is like (i.e., regarded as) a murderer or one whose worship is ritually defiled or idolatrous. The translation above assumes that the language is not metaphorical, but descriptive of the sinners’ hypocritical behavior. (Note the last two lines of the verse, which suggests they are guilty of abominable practices.) On the one hand, they act pious and offer sacrifices; but at the same time they commit violent crimes against men, defile their sacrifices, and worship other gods.
6 Heb “one who sacrifices a lamb, one who breaks a dog’s neck.” Some understand a comparison, but see the previous note. The significance of breaking a dog’s neck is uncertain, though the structure of the statement when compared to the preceding and following lines suggests the action is viewed in a negative light. According to Exod 13:13 and 34:20, one was to “redeem” a firstborn donkey by offering a lamb; if one did not “redeem” the firstborn donkey in this way, then its neck must be broken. According to Deut 21:1–9 a heifer’s neck was to be broken as part of the atonement ritual to purify the land from the guilt of bloodshed. It is not certain if these passages relate in any way to the action described in Isa 66:3.
7 Heb “one who offers an offering, pig’s blood.” Some understand a comparison, but see the note at the end of the first line.
8 Heb “one who offers incense as a memorial offering, one who blesses something false.” Some understand a comparison, but see the note at the end of the first line. אָוֶן (’aven), which has a wide variety of attested nuances, here refers metonymically to an idol. See and 20 2.
9 Heb “also they have chosen their ways.”
10 Heb “their being [or “soul”] takes delight in their disgusting [things].”

In other versions

ESVEnglish Standard Version

“He who slaughters an ox is like one who kills a man;

he who sacrifices a lamb, like one who breaks a dog’s neck;

he who presents a grain offering, like one who offers pig’s blood;

he who makes a memorial offering of frankincense, like one who blesses an idol.

These have chosen their own ways,

and their soul delights in their abominations;

NIVNew International Version (2011)

But whoever sacrifices a bull

is like one who kills a person,

and whoever offers a lamb

is like one who breaks a dog’s neck;

whoever makes a grain offering

is like one who presents pig’s blood,

and whoever burns memorial incense

is like one who worships an idol.

They have chosen their own ways,

and they delight in their abominations;

CSBChristian Standard Bible

One person slaughters an ox, another kills a person;

one person sacrifices a lamb, another breaks a dog’s neck;

one person offers a grain offering, another offers pig’s blood;

one person offers incense, another praises an idol—

all these have chosen their ways

and delight in their abhorrent practices.

NLTNew Living Translation

But those who choose their own ways—

delighting in their detestable sins—

will not have their offerings accepted.

When such people sacrifice a bull,

it is no more acceptable than a human sacrifice.

When they sacrifice a lamb,

it’s as though they had sacrificed a dog!

When they bring an offering of grain,

they might as well offer the blood of a pig.

When they burn frankincense,

it’s as if they had blessed an idol.

LEBThe Lexham English Bible

The one who slaughters a bull strikes a man;

the one who slaughters a lamb for sacrifice breaks the neck of a dog.

The one who offers an offering, the blood of swine;

the one who offers frankincense blesses an idol.

Indeed, they themselves have chosen their ways,

and their soul delights in their abhorrence.

KJV 1900King James Version

He that killeth an ox is as if he slew a man;

He that sacrificeth a lamb, as if he cut off a dog’s neck;

He that offereth an oblation, as if he offered swine’s blood;

He that burneth incense, as if he blessed an idol.

Yea, they have chosen their own ways,

And their soul delighteth in their abominations.

Public Domain