> Thanks, that works fine:
>
> \definefont[arabicamiri][file:amiri-regular.ttf*arabic at 15pt]
> \definefont[arabicuth][file:UthmanicHafs1Ver09.ttf*arabic at 17pt]
> \def\eoa#1{#1\char"06DD}
> \starttext
> \setupalign[r2l]
> \arabicuth لأَفَبِهَـٰذَا ٱلْحَدِيثِ أَنتُم مُّدْهِنُونَ ﴿٨١﴾\eoa
> \stoptext

Now I could locate the error in ConText better, see this code and the 
mistake, which occurs:

\definefont[arabicuth][file:UthmanicHafs1Ver09.ttf*arabic at 17pt]
\define[1]\eoa{#1\char"06DD}
\starttext
\setupalign[r2l]
\arabicuth

إِنَّ ٱلَّذِينَ كَفَرُوا سَوَآءٌ عَلَيْهِمْ ءَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لَا يُؤْمِنُونَ ﴿٦﴾\blank

إِنَّ ٱلَّذِينَ كَفَرُوا سَوَآءٌ عَلَيْهِمْ ءَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لَا يُؤْمِنُونَ ﴿٦٦﴾
\stoptext

(I have attached the compiled PDF).

The first aya, with a single one-digit number is not regonized 
correctly, but the second is (with a two-digit-number). Why?

Huseyin