Or HaChaim on Genesis
ויעש נח ככל אשר צוהו השם. Noach did in accordance with all that G'd commanded him. Rashi comments that this refers to his entering the ark. If that were the meaning there was no need for the Torah's comment as the Torah spells this out in 7,7 as well as 7,13.
Radak on Genesis
ויעש נח, he entered the ark together with the animals slated for survival, as mentioned in ויבא נח in verse 7.