Azhar was 85 not out, and Younis on 77 at the second interval, having scored more than four an over in the middle session.
Their unbeaten 138 runs for the third wicket was a Pakistan record against Bangladesh, after the hosts produced a disciplined opening session to reduce them to 58-2.
Azhar became the 16th Pakistani to reach 3,000 Test runs when he made 66.
He revived Pakistan after fast bowler Mohammad Shahid removed the in-form Mohammad Hafeez, who scored a double century in the previous Test, in the fourth over. Hafeez, on 8, tried to defend a delivery that angled in but straightened, and gave an edge behind.
With some grass on the pitch, the pacers were supposed to enjoy a good day, but Bangladesh was left one pacer short after Shahadat Hossain hobbled off the field following his second delivery.
Shahadat returned to took a catch of Sami Aslam on 19 off left-arm spinner Taijul Islam.
He was due to bowl after lunch, but during the break he twisted his right knee to be ruled out of the test.
His teammates bowled tirelessly without luck, as Younis and Azhar scored 126 runs in the session.
Azhar was closing in on his eighth Test century, and Younis his 29th.

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