Observation of the decay ${D}_{s}^{+}\to \omega {\pi }^{+}\eta $

Using $7.33\text{}\text{}{\mathrm{fb}}^{-1}$ of ${e}^{+}{e}^{-}$ collision data collected by the BESIII detector at c.m. energies between 4.128 GeV and 4.226 GeV, we observe for the first time the decay ${D}_{s}^{±}\to \omega {\pi }^{±}\eta $ with a statistical significance of $7.6\sigma $. The measured branching fraction of this decay is $\left(0.54±0.12±0.04\right)%$, where the first uncertainty is statistical and the second is systematic.