The hidden-charm pentaquark Pc(4450) observed recently by the LHCb collaboration may be of molecular nature, as advocated by some unitary approaches that also predict pentaquark partners in the strangeness S=−1 sector. In this work we argue that a hidden-charm strange pentaquark could be seen from the decay of the Λb, just as in the case of the non-strange Pc(4450), but looking into the J/ψηΛ decay mode and forming the invariant mass spectrum of J/ψΛ pairs. In the model presented here, which assumes a standard weak decay topology and incorporates the hadronization process and final-state interaction effects, we find the J/ψηΛ final states to be populated with similar strength as the J/ψK−p states employed for the observation of the non-strange pentaquark. This makes the Λb→J/ψηΛ decay to be an interesting process to observe a possible strange partner of the Pc(4450). We study the dependence of the J/ψΛ mass spectra on various model ingredients and on the unknown properties of the strange pentaquark.