Child's Pose (Balasana) is one of the most universally recommended resting poses in yoga, and for back pain specifically, its main value is gentle decompression of the lower spine.
Getting the position right
Kneel with the big toes together and knees as wide as is comfortable, then sit the hips back toward the heels while walking the hands forward and resting the forehead on the mat or a block.
Why knee width matters
Wider knees reduce pressure on the belly and lower back, making the fold deeper and more comfortable — narrower knees create a more compact, restful shape. Neither is 'more correct'; it's a matter of what feels supportive that day.
What it's actually doing for the back
The gentle forward fold combined with hip flexion takes weight-bearing pressure off the lumbar spine, which is why it's so often used as a reset or rest point between more active poses.
Is it normal for Child's Pose to feel uncomfortable on the knees?
Some knee sensitivity is common if the knees are unaccustomed to full flexion — placing a folded blanket behind the knees, or widening the knee position, usually resolves it.