Allāh, the Most High said:

فَلِذَلِكَ فَادْعُ وَاسْتَقِمْ كَمَا أُمِرْتَ وَلَا تَتَّبِعْ أَهْوَاءَهُمْ

“So unto this [religion of Allāh] invite, and remain steadfast as you are commanded and do not follow their desires.” (al-Shura 42:15)

Shaykh Ibn Bāz (raḥimahullāh): One should call to Allāh accompanied by uprightness (istiqāmah) —so that one is a caller to Allāh through both action and speech. The one who calls to Allāh invites others using the verses and hadiths, and also invites to Allāh through his own character—through his own uprightness upon the truth—so that people see his actions matching his words.

“So unto this [religion of Allāh] invite, and remain steadfast.” And in the other verse: “So remain upright as you have been commanded, and those who have repented with you, and do not transgress.” [Hūd 11:112].

Source: Explanation of Tafsīr Ibn Kathīr, Sūrah al-Shūrā.