Answer
In the name of Allah 
The Dua is as follow
قَالَ رَبِّ اشْرَحْ لِي صَدْرِي
Qala rabbishrah lee [s]adree
وَيَسِّرْ لِي أَمْرِي
Wayassir lee amree
وَاحْلُلْ عُقْدَةً مِنْ لِسَانِي
Wahlul 'Uqdatam-mil-li saanee
يَفْقَهُوا قَوْلِي
Yafqahoo qawlee
(Surah Ta-Ha, verse 25-028)
He (Mosaa) said: "O my Lord! Expand for me my breast;
"Ease my task for me;
"And remove the impediment from my speech,
"So they may understand what I say:
And Allah knows best
28 Oct 2005
Batley, U.K
Founder of the "Islamic Foundation for Theology and Research" (I.F.T.A.R)