﴿ ۞ وَمَن يَقْنُتْ مِنكُنَّ لِلَّهِ وَرَسُولِهِۦ وَتَعْمَلْ صَٰلِحًۭا نُّؤْتِهَآ أَجْرَهَا مَرَّتَيْنِ وَأَعْتَدْنَا لَهَا رِزْقًۭا كَرِيمًۭا ﴾

“But if any of you devoutly obeys God and His Apostle and does good deeds, on her shall We bestow her reward twice-over: for We shall have readied for her a most excellent sustenance [in the life to come].”

The consorts of the Prophet had the position of leaders in the society. Such people have to make greater sacrifices than those made by ordinary people. That is why God has promised a double reward for such people. They use more will power than others in the performance of a (good) deed and that is why they receive greater credit for it. The Prophet’s consorts in view of their qualities used to come in contact with others very often. People used to come to them to seek guidance on religious matters. That is why they were instructed to adopt a slightly dry tone while talking to others and not talk to them informally and familiarly as one is likely to do in the case of near relatives (in respect of whom marriage is not permissible).