The authors demonstrate that the spin Hall effect (SHE) in a thin film with strong spin-orbit scattering can excite magnetic precession in an adjacent ferromagnetic film. By applying a microwave-frequency charge current through a Pt/NiFe bilayer, an oscillating transverse spin current is generated in the Pt, which transfers spin angular momentum to the NiFe, inducing ferromagnetic resonance (FMR) dynamics. The Oersted field from the current also generates an FMR signal with a different symmetry. The ratio of these two signals allows a quantitative determination of the spin current and the spin Hall angle. The experiment uses Pt/Permalloy (Py = Ni$_{81}$Fe$_{19}$) bilayers, where the oscillating spin current is injected into the Py, causing magnetization precession and a significant oscillation of the bilayer resistance. The resonance properties enable a direct quantitative measure of the spin current absorbed by the Py. The results show that the spin current density in the Py is $J_s/J_c = 0.056 \pm 0.005$ for Pt(6)/Py(4), implying a spin Hall angle $\theta_{SH} > 0.056$. This technique provides a straightforward and self-calibrated method to measure the efficiency of spin current generation in metallic films, which is promising for applications that might utilize the SHE to manipulate ferromagnet dynamics.The authors demonstrate that the spin Hall effect (SHE) in a thin film with strong spin-orbit scattering can excite magnetic precession in an adjacent ferromagnetic film. By applying a microwave-frequency charge current through a Pt/NiFe bilayer, an oscillating transverse spin current is generated in the Pt, which transfers spin angular momentum to the NiFe, inducing ferromagnetic resonance (FMR) dynamics. The Oersted field from the current also generates an FMR signal with a different symmetry. The ratio of these two signals allows a quantitative determination of the spin current and the spin Hall angle. The experiment uses Pt/Permalloy (Py = Ni$_{81}$Fe$_{19}$) bilayers, where the oscillating spin current is injected into the Py, causing magnetization precession and a significant oscillation of the bilayer resistance. The resonance properties enable a direct quantitative measure of the spin current absorbed by the Py. The results show that the spin current density in the Py is $J_s/J_c = 0.056 \pm 0.005$ for Pt(6)/Py(4), implying a spin Hall angle $\theta_{SH} > 0.056$. This technique provides a straightforward and self-calibrated method to measure the efficiency of spin current generation in metallic films, which is promising for applications that might utilize the SHE to manipulate ferromagnet dynamics.