إِنَّ الَّذِينَ هُم مِّنْ خَشْيةِ رَبِّهِمْ مُّشْفِقُونَ
(Verily, those who live in awe for fear of their Lord;) means, even though they have reached the level of Ihsan and have faith and do righteous deeds, they are still in awe of Allah and fear Him and His hidden plans for them, as Al-Hasan Al-Basri said, "The believer combines Ihsan with awe, while the disbelievers combine evil deeds with a sense of security."
وَالَّذِينَ هُم بِـَايَـتِ رَبَّهِمْ يُؤْمِنُونَ
(And those who believe in the Ayat of their Lord;) means, they believe in His universal and legislative signs, as Allah says about Maryam, peace be upon her:
وَصَدَّقَتْ بِكَلِمَـتِ رَبَّهَا وَكُتُبِهِ
(and she testified to the truth of the Words of her Lord, and His Scriptures) 66:12, meaning that she believed that whatever existed was by the will and decree of Allah, and that whatever Allah decreed, if it was a command, it would be something that He liked and accepted; if it was a prohibition, it would be something that He disliked and rejected; and if it was good, it would be true. This is like the Ayah:
وَالَّذِينَ هُم بِرَبِّهِمْ لاَ يُشْرِكُونَ
(And those who join not anyone (in worship) as partners with their Lord;) meaning, they do not worship anyone or anything else besides Him, but they worship Him Alone and know that there is no god except Allah Alone, the One, the Self-Sufficient Master, Who does not take a wife or have any offspring, and there is none comparable or equal unto Him.
وَالَّذِينَ يُؤْتُونَ مَآ ءاتَواْ وَّقُلُوبُهُمْ وَجِلَةٌ أَنَّهُمْ إِلَى رَبِّهِمْ رَجِعُونَ
(And those who give that which they give with their hearts full of fear, because they are sure to return to their Lord.) means, they give in charity, fearing that it may not be accepted from them because of some shortcoming or failure to meet the required conditions of giving. This has to do with fear and taking precautions, as Imam Ahmad recorded from `A'ishah: I said: "O Messenger of Allah ﷺ,
وَالَّذِينَ يُؤْتُونَ مَآ ءاتَواْ وَّقُلُوبُهُمْ وَجِلَةٌ
(And those who give that which they give with their hearts full of fear...) Are these the ones who steal and commit Zina and drink alcohol while fearing Allah" The Messenger of Allah ﷺ replied:
«لَا، يَا بِنْتَ أَبِي بَكْرٍ يَا بِنْتَ الصِّدِّيقِ، وَلَكِنَّهُ الَّذِي يُصَلِّي وَيَصُومُ وَيَتَصَدَّقُ وَهُوَ يَخَافُ اللهَ عَزَّ وَجَل»
(No, O daughter of Abu Bakr. O daughter of As-Siddiq, the one who prays, fast and gives in charity, fearing Allah.) This was recorded by At-Tirmidhi, and Ibn Abi Hatim recorded something similar in which the Prophet said:
«لَا يَا بِنْتَ الصِّدِّيقِ، وَلَكِنَّهُمُ الَّذِينَ يُصَلُّونَ وَيَصُومُونَ وَيَتَصَدَّقُونَ وَهُمْ يَخَافُونَ أَلَّا يُقْبَلَ مِنْهُمْ:
أُوْلَـئِكَ يُسَـرِعُونَ فِى الْخَيْرَتِ»
(No, O daughter of As-Siddiq, they are the ones who pray and fast and give in charity while fearing that it will not be accepted from them, (It is these who hasten in the good deeds.)) This is also how Ibn `Abbas, Muhammad bin Ka`b Al-Qurazi and Al-Hasan Al-Basri interpreted this Ayah.