Bi-S bond is relatively more stronger than Bi-N bond. How can you explain this with HSAB concept?

A qualitative correlation between the extent of interaction between various Lewis acids and bases has been achieved by classifying the acids or bases into two classes: hard and soft in his theory of Hard and Soft Acids and Bases – HSAB. Acid-base reactions are then treated by the general principle that hard acids prefer to combine with hard bases and soft acids prefer to combine with soft bases (and vice versa). The criterion of hardness (or softness) is ascribed to the “hardness” of the electron cloud associated with any species. A firmly held electron-cloud with low polarizability makes a species “hard”, while an easily polarizable electron cloud characterizes the species as “soft”. A third category with intermediate character appears in the borderline.

Based on this information, tell us your best guess.

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons