There the believers were tested and shaken with a severe shaking. (33:11)

Almuntakhab Fi Tafsir Alquran Alkarim

There and in that extreme situation were those who conformed to Islam tested. Their actions, their thoughts and their disposition mirrored their spirit-high or low and their will -poor or strong- in the face of the extreme danger which really shook them and quaked them with fear

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(33:11) The believers were then put to a severe test and were most violently convulsed. *21

There the believers were tested and shaken with a severe shaking. meaning

*21) "The believers" : All those who accepted the Holy Prophet as Allah's Messenger and became included among his followers, which comprised both the true believers and the hypocrites. In this paragraph Allah has made mention of the Muslim community as a whole. In the following three paragraphs the attitude of the hypocrites has been commented upon, and the next two deal with the Holy Prophet and the true believers.
 

There the believers were tested and shaken with a severe shaking. meaning in Urdu

اُس وقت ایمان لانے والے خوب آزمائے گئے اور بُری طرح ہلا مارے گئے