In this 2010 interview to Iftikhar Ahmed, general Ziauddin Butt -- who remained Pak's army chief for ~ 3 hours until Musharraf's coup -- tells the story of his meeting with Mullah Omar in 1999 as DG ISI. Some interesting nuggets:

Butt says he confronted Mullah Omar with taking money from Bin Laden but Omar said (inexact translation) "he hasn't given me even 2 rupees."

Mullah Omar complained to Butt that the entire world calls him a "tourist." Butt corrected Omar, telling him the world calls him a "terrorist", not "tourist", which is a dangerous label.

On why he wouldn't hand over or expel Bin Laden, Omar said that Bin Laden was like a bone in the throat that can neither be swallowed nor thrown out, and that if he acted against Bin Laden, Taliban foot soldiers will murder him.

Listen for yourself here at 50:55: