We observe the dynamics of waves propagating on the surface of a ferrofluid under theinfluence of a spatially and temporally modulated field. In particular, we exciteplane waves by applying a traveling lamellar modulation of the magnetization. Bymeans of this external driving, both the wavelength and the propagation velocityof the waves can be controlled. The amplitude of the excited waves exhibits aresonance phenomenon similar to that of a forced harmonic oscillator. Its analysisreveals the dispersion relation of the free surface waves, from which the criticalmagnetic field for the onset of the Rosensweig instability can be extrapolated.