Treasury of Scripture
they brought The law only required one bullock for the sins of the high priest, another for the sins of the people, and one he-goat for the sins of the prince: but Hezekiah offered many more, and the reason appears sufficiently evident: the law only speaks of the sins of ignorance, but here there were sins of every dye, idolatry, apostasy from the Divine worship, profanation of the temple, etc. The sin offerings, we are informed, were offered, first, for the Kingdom, for the transgressions of the king and his family; secondly, for the sanctuary, which had been defiled and polluted; and for the priests, who had been profane, negligent, and unholy; and finally, for Judah, for the whole mass of the people, who had been led away into every kind of abomination by the above examples.
seven
Numbers 23:1,14,29 And Balaam said to Balak, Build me here seven altars, and prepare me here seven oxen and seven rams...
1 Chronicles 15:26 And it came to pass, when God helped the Levites that bore the ark of the covenant of the LORD...
Ezra 8:35 Also the children of those that had been carried away, which were come out of the captivity, offered burnt offerings to the God of Israel...
Job 42:8 Therefore take to you now seven bullocks and seven rams, and go to my servant Job, and offer up for yourselves a burnt offering...
Ezekiel 45:23 And seven days of the feast he shall prepare a burnt offering to the LORD...
a sin offering
Leviticus 4:3-14 If the priest that is anointed do sin according to the sin of the people; then let him bring for his sin, which he has sinned...
Numbers 15:22-24 And if you have erred, and not observed all these commandments, which the LORD has spoken to Moses...