Gleanings — Paragraph 702
Source (Arabic)
قد کتب الله لکلّ نفس تبلیغ أمره والّذي أراد ما أمر به ینبغي له أن یتّصف بالصّفات الحسنة أوّلاً ثمّ یبلّغ النّاس لتنجذب بقوله قلوب المقبلین ومن دون ذلک لا یؤثّر ذکره في أفئدة العباد...
Translation
Whoever ariseth to discharge this duty, must needs, ere he proclaimeth His Message, adorn himself with the ornament of an upright and praiseworthy character, so that his words may attract the hearts of such as are receptive to his call. Without it, he can never hope to influence his hearers.