Mishkat al-Masabih 1149
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