Towards the end of his al-Ghayth al-Musajjam fī Sharḥ Lāmīyat al-ʿAjam, Khalīl ibn Aybak al-Ṣafadī (d. 1363/764) aims a peculiar slight at his sometime teacher Ibn Taymiyya (d. 1328/728), likening him to two famous executed heretics, al-Suhrawardī (d. circa 1191/587) and Ibn al-Muqaffaʿ (d. 759/142), in their shared ‘lack of reason’. Though often cited as evidence that al-Ṣafadī held his famous contemporary’s intelligence in low regard, the insult is more specifically aimed at his lack of discretion. In this article, I examine how Ibn Taymiyya is portrayed across the Sharḥ and argue that, when paired with insights from the book about al-Ṣafadī’s own language-centred hermeneutics, we gain a number of interesting insights into this prolific historian and adīb. The first is that he was closely familiar with and even mimicked aspects of the culture of ‘esoteric disclosure’, including in his criticism of Ibn Taymiyya and his indiscretion. Al-Ṣafadī also emerges as something of an exemplar of what Thomas Bauer has called Islam’s ‘cultural ambiguity’, whose final criticism of Ibn Taymiyya and of the heretics to whom he is likened is not any specific one of their beliefs, but rather their inability to exercise discretion in expressing them.