How do I get muffle enchant?

How do I get the muffle enchant, so I can enchant boots with it? I already have some quest boots, with it on, but I can't seem to disenchant them.

There are no unique items that can be disenchanted for the muffle enchant.

I'm afraid you're going to have to luck out and find a set of "[Any boots] of Muffling" to disenchant, which I will tell you now, is not easy.

I easily reset a shopkeeper's inventory 500+ times with no luck before I finally used the console to spawn myself a set of steel boots of muffling and took 100,000 gold out of my inventory.

player.additem 92a75 1 if you want to do that yourself.

Source

You have to buy it or loot it, then disenchant it in order to learn it. You might have a better chance of finding one in the Thieves Guild.

My fist time through the game I found a pair of leather boots with the muffle enchant on them and that is how I got it. You cannot disenchant an piece of special equipment with the enchant on it how ever. Its not a bug, for example the boots you get for joining the Dark Brotherhood have the enchant with muffle on it but you cant disenchant those. Its all prety much random and requires a rather large amount of luck.