ما ثبت بدليل فيه شبهة
Wajib is a ruling established through evidence in which a legally relevant degree of uncertainty remains.
Here shubhah does not mean that the evidence is false or unreliable. It indicates an absence of the certainty characteristic of a definitive proof, perhaps in transmission or interpretation. An interpreted verse or a sound solitary report can supply examples of such evidence.
A binding wajib still requires sound legal reasoning. Mere preference, an unsupported report, or a casual opinion does not create an obligatory ruling.