أُوْلَيِكَ يُوْتَوْنَ أَجْرَهُم مَّرَّتَيْنِ بِمَا صَبَرُوا
These will be given their reward twice over, because they are patient,
means, those who have this characteristic -- that they believed in the first Book and then in the second.
Allah says;
بِمَا صَبَرُوا
(because they are patient), meaning, in their adherence to the truth, for taking such thing upon oneself is not easy for people.
It was reported in the Sahih from the Hadith of Amir Ash-Sha`bi from Abu Burdah that Abu Musa Al-Ash`ari, may Allah be pleased with him, said that the Messenger of Allah said;
ثَلَثَةٌ يُوْتَوْنَ أَجْرَهُمْ مَرَّتَيْنِ
رَجُلٌ مِنْ أَهْلِ الْكِتَابِ امَنَ بِنَبِيِّهِ ثُمَّ امَنَ بِي
وَعَبْدٌ مَمْلُوكٌ أَدَّى حَقَّ اللهِ وَحَقَّ مَوَالِيهِ
وَرَجُلٌ كَانَتْ لَهُ أَمَةٌ فَأَدَّبَهَا فَأَحْسَنَ تَأْدِيبَهَا ثُمَّ أَعْتَقَهَا فَتَزَوَّجَهَا
There are three who will be given their reward twice;
a man among the People of the Book who believed in his Prophet then believed in me;
a slave who fulfills his duty towards Allah and towards his master; and
a man who has a slave woman and educates her and teaches her good manners, then he frees her and marries her.
Imam Ahmad recorded that Abu Umamah said;
"On the day of the Conquest (of Makkah) I was walking alongside the Messenger of Allah as he was riding, and he said some very beautiful words, including the following;
مَنْ أَسْلَمَ مِنْ أَهْلِ الْكِتَابَيْنِ فَلَهُ أَجْرُهُ مَرَّتَيْنِ وَلَهُ مَا لَنَا وَعَلَيْهِ مَا عَلَيْنَا وَمَنْ أَسْلَمَ مِنَ الْمُشْرِكِينَ فَلَهُ أَجْرُهُ وَلَهُ مَا لَنَا وَعَلَيْهِ مَا عَلَيْنَا
Whoever among the people of the two Books becomes Muslim, he will have his reward twice, and he has the same rights and duties as we do. Whoever among the idolators becomes Muslim will have one reward, and he has the same rights and duties as we do."
Allah's saying;
وَيَدْرَوُونَ بِالْحَسَنَةِ السَّيِّيَةَ
and repel evil with good,
means, they do not respond to evil in kind, rather they forgive and overlook.
وَمِمَّا رَزَقْنَاهُمْ يُنفِقُونَ
and spend out of what We have provided for them.
meaning, `from the lawful provision that We have given them, they spend on their families and relatives as they are required to do, and they pay Zakah and give voluntary charity.