Mishkat al-Masabih

He said: If anyone raises and lowers his head before the imam, his forelock is in the devil’s hand. Malik transmitted it.

وَعنهُ قَالَ: الَّذِي يَرْفَعُ رَأْسَهُ وَيَخْفِضُهُ قَبْلَ الْإِمَامِ فَإِنَّمَا ناصيته بيد الشَّيْطَان ". رَوَاهُ مَالك