Shaykhul-Islam Ibn Taymiyyah (may Allāh have mercy upon him):

If the person who speaks the truth intends (with that) being uppermost in the land (over the people) and/or causing corruption therein, then he is on the same level as the one who fights out of fanaticism and showing off. On the other hand, if the person speaks (the truth) sincerely for the sake of Allāh, making the religion for Him (Alone), he is from the Mujāhidīn (i.e. those who  strive) on the path of Allāh; (he is from the) inheritors of the Prophets (and) the successors of the Messengers.

Source: Al-Fatāwā, 28/235

Translated by Abu Yusuf Khaleefah
30th of Muḥarram, 1437 AH (11/13/2015)
Masjid Nur Allah, Queens, NY

Original Arabic

بسم الله الرحمن الرحيم

قال شيخ الإسلام ابن تيمية رحمه الله:

لو تكلم (المتكلم) بالحق لقصد العلو في الأرض أو الفساد كان بمنزلة الذي يقاتل حمية ورياءً, وإن تكلم لأجل الله تعالى مخلصاً له الدين كان من المجاهدين في سبيل الله, من ورثة الأنبياء, خلفاء الرسل

الفتاوى: 235/28