וַיִּקְח֣וּ בְנֵֽי־אַ֠הֲרֹן נָדָ֨ב וַאֲבִיה֜וּא אִ֣ישׁ מַחְתָּת֗וֹ וַיִּתְּנ֤וּ בָהֵן֙ אֵ֔שׁ וַיָּשִׂ֥ימוּ עָלֶ֖יהָ קְטֹ֑רֶת וַיַּקְרִ֜בוּ לִפְנֵ֤י יְהוָה֙ אֵ֣שׁ זָרָ֔ה אֲשֶׁ֧ר לֹ֦א צִוָּ֖ה אֹתָֽם׃
Kinuha ng mga anak ni Aaron na sina Nadab at Abihu ang kani-kanilang suuban, nilagyan nila ito ng apoy, at pinatungan ng insenso. At naghandog sila sa harap ng Walang-Hanggan ng ibang apoy na hindi Niya iniutos sa kanila.
Or HaChaim
וידבר ה׳ אל משה אחרי מות, G'd spoke to Moses after the death, etc. Why doesn't the Torah spell out what G'd told Moses on this occasion? Secondly, why did the Torah have to add that this communication occurred after the death of two of Aaron's sons? What bearing does this have on the content of G'd's message? Thirdly, why did the Torah have to add the words: בקרבתם לפני ה׳ וימותו, "when they came close to the presence of G'd and died?" If the Torah wanted to tell us the reason these sons died, we have been told this already in Leviticus 10,1, when the Torah wrote: ויקריבו לפני ה׳ אש זרה? The Torah was far more specific about the death of these sons in that context than it is here. We could not determine what the sin of these sons of Aaron had been by relying merely on what the Torah has written here. What is so terrible about wanting to come close to the presence of G'd? Fourthly, the word וימותו, they died, is quite superfluous seeing the verse commenced with the mention of their deaths? Fifthly, why did the Torah use the additional letter ו in the word וימותו?
Tur HaArokh
בקרבתם לפני ה' וימותו, “when they approached the presence of Hashem and died.” Ibn Ezra comments that this verse is proof that the sons of Aaron died because they had dared to bring the incense into the Tabernacle. Nachmanides disagrees, as the Torah always mentions the sin of anyone who died an untimely death at the hands of Hashem. The Torah had already told us on a number of occasions that the cause of death was that they introduced “strange fire” which they had not been authorised to do. (Leviticus 10,1) However, this was described as בהקריבם אש זרה, “when they introduced alien fire,” whereas here the Torah wrote about בקרבתם, i.e. when they personally entered a domain which was out of bounds to them. It is therefore completely reasonable that the Torah should now warn Aaron not to enter the wrong place at the wrong time. Although he is permitted entry to the Holy of Holies, even, something no other priest is allowed to enter, he cannot do so at times of his choosing. It is quite possible that the correct interpretation of our verse is in line with what our sages said (Mechilta Beshalach ויסע ו) that the people had come to the conclusion that the incense contained poisonous herbs which had caused the death of Nadav and Avihu, the 250 men who offered incense during Korach’s rebellion, etc. The Torah, countering these wild accusations leveled against the incense offering, wanted to make the point that it had not been the incense which had killed them but their unauthorised entry, both in terms of place and time. Aaron therefore had to be especially on guard, seeing he would offer incense on a daily basis he would be more exposed to such a danger than any other individual. The Torah defines precisely when, where, and who is fit to offer this special offering (verses 12 and 13). Some scholars feel that we must take careful note of the difference in meaning of the word בקרבתם as opposed to בהקריבם, the former referring to the act of entering a forbidden domain regardless of the purpose why it was entered and regardless of what the person entering had in his hands as an offering. In order to make plain that mere entering the sacred domain by Nadav and Avihu was a mortal sin by itself, the Torah now instructs Aaron: בזאת יבא אהרן אל הקוד'ש, “only when accompanied by the following is Aaron allowed to enter these holy domains.”
Haamek Davar
And his sons with him. The expression “with him” implies that they only merited the priesthood through being Aharon’s sons. This was the error of Nadav and Avihu when they offered the strange fire before God (Vayikra 10:1)—they thought they were worthy of performing the service on account of their own personal greatness.