Tafsir of Surah As-Saff 61:3

﴿كَبُرَ مَقْتًا عِندَ اللَّهِ أَن تَقُولُوا مَا لَا تَفْعَلُونَ﴾

Greatly hateful in the sight of Allāh is that you say what you do not do.

English Translation - Noor International Center — v1.1.2 · QuranEnc.com

The words of the two imams are given in their original Arabic, verbatim, with references.

Shaykh al-Islam Ibn Taymiyyah

أي كبر ممقوتا أي كبر مقته مقتا«الاستقامة» 1/18