Measurement of the branching fraction of $\text{psip}\to \omega \eta \eta$

Using a sample of (2.712 $\pm$ 0.014)$\times {10}^9$ $\text{psip}$ events collected with the BESIII detector at the BEPCII collider in 2009, 2012, and 2021, the decay $\text{psip}\to \omega \eta \eta$ is observed for the first time. The branching fraction of the $\psi (3686)\to \omega \eta \eta$ decay is measured to be (1.65 $\pm$ 0.02 $\pm$ 0.21)$\times {10}^{-5}$, where the first uncertainty is statistical and the second systematic. Clear structures associated with the well-established $\omega (1420)$ and $f_0(1710)$ resonances are observed in the $\omega \eta$ and $\eta \eta$ invariant-mass spectra, respectively.