${\mathrm{PH}}_3$ is also basic in nature, but ${\mathrm{PH}}_3$ is less basic in comparison to ${\mathrm{NH}}_3$. The stability of hydrides decreases down the group.

The order of basicity hydrides of Group 15 elements is shown below:

${\mathrm{NH}}_{3 }> {\mathrm{PH}}_3 > {\mathrm{AsH}}_3 > {\mathrm{SbH}}_3 \ge {\mathrm{BiH}}_3$.