The dreadful Sansloy kills the lion, puts Una on his horse and rides away, deaf to her pleas. Her faithful palfrey follows them, thus ending Canto 3. Canto 4 begins with an exhortation to all the knights to be always faithful to their ladies and not to believe to readily in any stories about their unfaithfulness, lest they end up like Redcrosse, who is now being led astray by the new object of his affections. This piece of advice is theoretically good, at least when it comes to the general principle – don’t believe in gossips – but taking into account that Redcrosse saw Una in bed with another man with his own eyes, it’s not that good in real life. Now Duessa leads our knight to the House of Pride, which is a beautiful castle, but treacherous. A broad road leads to it, and many people follow it, but few get out, and only as broken men. The house is built on sand, so its foundations are not safe and in fact it is already crumbling at the back, but the cracks have been skilfully hidden by paint. They are let in by the porter named Malvenu (a pun on the traditional name of the porter at the castle of love in courtly romances, who was called Benvenu), and they enter a hall, decked with costly tapestries, where a great deal of various people are waiting for the lady of this palace.
[Edit] I‘ve just read that the fact that the Palace of Pride is covered with golden foil is the symbol of hypocrisy, because that is what hypocrisy literally means in Greek – hyper (over) + chrysos (gold). I was quite excited about it, until I’ve read that the OED gives a different etymology, But maybe Spenser was not quite up to speed with his Greek studies and this is a kind of folk etymology he was familiar with.