Hello ahmad,
Which version you are using?
You can check this report which is standard and available in Organization administration > Workflow > Workflow history.
But this report will not give you the detail like, pending with which user as you are expecting. You can check if you can add a new column called "User" through personalization or not. If not possible, then you can ask the developer to add a new column in this report to display the pending user name.
You will find the details of pending user from the workflow history page itself. Below link looks similar discussion on the same.
https://community.dynamics.com/ax/f/microsoft-dynamics-ax-forum/209928/list-of-pending-workflows-for-a-particular-user-from-admin-login?pifragment-96834=1
Else; you can create a new report and add the same details there.
In one of my implementation; we had the same requirement and we just created a new report named as Workflow pending item list. If you look at this report, you will see the "Submitted by" and "Pending with" details.

For your understanding, I have attached the excel format too.
[View:/cfs-file/__key/communityserver-discussions-components-files/765/Workflow-Pending-Item-List.xlsx]
Kindly check and provide your feedback.
Best regards,
Sourav Dam
Kindly mark this thread 'Yes' if this is answered your query which may help other community members in this forum.