Tafsir of Al-Qasas 28:34

وأخي هارون هو أفصح مني لسانا

And my brother Harun -- he is more eloquent in speech than me, Musa, peace be upon him, had a speech defect, because when he had been given the choice between a date and a pearl, he mistakenly picked up a coal and placed it on his tongue, so he found it difficult to speak clearly. Musa said:

واحلل عقدة من لسانى

يفقهوا قولي

واجعل لى وزيرا من أهلى

هرون أخى

اشدد به أزرى

وأشركه فى أمرى

"And loose the knot (the defect) from my tongue. That they understand my speech. And appoint for me a helper from my family, Harun, my brother. Increase my strength with him, And let him share my task.'' (20:27-32) meaning, `give me someone to keep me company in this immense task of Prophethood and conveying the Message to this arrogant, tyrannical and stubborn king.' Hence Musa said:

وأخي هارون هو أفصح مني لسانا فٲرسله معي ردءا

(And my brother Harun -- he is more eloquent in speech than me: so send him with me as a helper), meaning, as a support to give strength to my cause and confirm what I say and convey from Allah, because the word of two carries more weight in people's minds than the word of one.

فٲرسله معي ردءا يصدقني

send him with me as a helper to confirm me. So he said:

إني أخاف أن يكذبون

Verily, I fear that they will deny me. Muhammad bin Ishaq said:

ردءا يصدقني

(as a helper to confirm me), means, `to explain to them what I say, for he can understand me where they may not.' When Musa asked for this, Allah said to him: