Quran, Chapter 48, Verse 29:
Muhammad is the messenger of Allah. And those with him are hard against the disbelievers and merciful among themselves. Thou (O Muhammad) seest them bowing and falling prostrate (in worship), seeking bounty from Allah and (His) acceptance. The mark of them is on their foreheads from the traces of prostration. Such is their likeness in the Torah and their likeness in the Gospel - like as sown corn that sendeth forth its shoot and strengtheneth it and riseth firm upon its stalk, delighting the sowers - that He may enrage the disbelievers with (the sight of) them.