Ahhhhh yes. Four-Limbed Staff Pose, the old standby, Chaturanga Dandasana. I've shared them before, but I love Ryan Conrad's yoga illustrations. It is the building block for all other strength work in yoga (in my opinion). If you're just starting yoga and want to get stronger, work this pose like crazy. If you practice Ashtanga, that won't be a problem because you'll do at least 60 chaturangas in the primary series alone (!!).
I find this pose to be one that scares off new students. When first instructed to do this, most people laugh and say "yeah right!" However, with a little diligence, it's easier than you think. Shoulder alignment is so important to do this pose safely. Because it is repeated so much in most vinyasa classes, it's important to be mindful of alignment. Here's a good article from Yoga Journal on this.
The other most important thing in order to master this pose? A sense of humor. For example, I really want this tank top