Translation:

4. When thou lookest at them their exteriors please thee; and when they speak thou listenest to their words. They are as (worthless as hollow) pieces of timber propped up (unable to stand on their own). They think that every cry is against them. They are the enemies; so beware of them. The curse of Allah be on them! How are they deluded (away from the Truth)!

Notes (Tafseer)

5468. Cf. ii. 7. Their double-dealing has fogged their understanding. In Arabic the heart is taken to be the seat of understanding as well as of affection.

5470. Good timber is strong in itself and can support roofs and buildings. Hollow timber is useless, and has to be propped up against other things. The Hypocrites are like rotten timber. They have no firm character themselves, and for others they are unsafe props to rely upon.

5471. Their conscience always troubles them. If any cry is raised, they immediately get alarmed, and think it is against themselves. Such men are worse than open enemies.