How did Hashem help the Leviyim?
'Rashi', Radak: They did not stumble in carrying it, like Uza stumbled the first time.
'Rashi', from Sotah 35a: This shows that the Aron carried itself. Radak: They did not feel any weight on their shoulders. They knew that Hashem helps them.
Vilna Gaon: The Leviyim did not carry the Aron, Rather, the Kohanim did. However, when the Kohanim saw that Hashem helps them, and the Aron carries its carriers, they put [the staves] on the Leviyim's shoulders, and it carried them. "Ha'Leviyim ha'Nos'im Es ha'Aron" (verse 27) means [that they were carried] with the Aron.
Why does it say here that they offered seven bulls and seven rams? In Shmuel II, 6:13, it says that after six steps they offered a bull and Meri!
Radak (Shmuel II, 6:13): There it says "va'Yizbach" (singular) ? David offered a bull and Meri. Here it says "va'Yizbechu" (plural) ? the Leviyim offered seven bulls and seven rams when they took the seventh step.
Radak (Shmuel II, 6:13, citing Sotah 35b) #1: After every step they offered an ox and Meri. After six steps they offered seven bulls and seven rams.
Radak (Shmuel II, 6:13, citing Sotah 35b) #2: After every six steps offered a bull and Meri. After six sets of steps they offered seven bulls and seven rams. Malbim (here and Shmuel II, 6:13) ? this is after 42 steps, corresponding to Hashem's 42-letter name. After six steps they offered a bull and Meri, to make the seventh Kodesh.
