(13:21) And those who join that which Allah has ordered to be joined and fear their Lord and are afraid of the evil of [their] account,
Muhammad Taqi-ud-Din al-Hilali and Muhammad Muhsin Khan,
(13:21) Those who join that which Allah has commanded to be joined (i.e. they are good to their relatives and do not sever the bond of kinship), fear their Lord, and dread the terrible reckoning (i.e. abstain from all kinds of sins and evil deeds which Allah has forbidden and perform all kinds of good deeds which Allah has ordained).
Mohammed Marmaduke William Pickthall
(13:21) Such as unite that which Allah hath commandeth should be joined, and fear their Lord, and dread a woeful reckoning;
Abdullah Yusuf Ali
(13:21) Those who join together those things which Allah hath commanded to be joined, hold their Lord in awe, and fear the terrible reckoning;
Mohammad Habib Shakir
(13:21) And those who join that which Allah has bidden to be joined and have awe of their Lord and fear the evil reckoning.
Dr. Ghali
(13:21) And who hold together what Allah has commanded to be held together, and are apprehensive of their Lord, and fear an odious reckoning,
Ali Unal
(13:21) And those who unite the bonds God has commanded to be joined (among kin as a requirement of blood relationship, and among people as required by human social interdependence), and stand in awe of their Lord, and fearful of (facing) the most evil reckoning;
Amatul Rahman Omar
(13:21) These are the persons who keep the ties (of love and relationship) Allâh has commanded to be kept, who hold their Lord in awe and who dread the evil reckoning.
Literal
(13:21) And those who connect what God ordered/commanded with it that (it) be connected , and they fear their Lord, and they fear the account`s/calculation`s evil .
Ahmed Ali
(13:21) Who keep together what God has ordained held together, and fear their Lord and dread the hardship of the Reckoning,
A. J. Arberry
(13:21) who join what God has commanded shall be joined, and fear their Lord, and dread the evil reckoning,
Abdul Majid Daryabadi
(13:21) And those who enjoin that which Allah hath commanded to be enjoined, and fear their Lord, and dread the evil reckoning;
Maulana Mohammad Ali
(13:21)-
Muhammad Sarwar
(13:21) who maintain all the proper relations that God has commanded them to maintain, who have fear of their Lord and the hardships of the Day of Judgment,
Hamid Abdul Aziz
(13:21) Those who fulfil the Covenant of Allah and break not the pact,
Faridul Haque
(13:21) Those who unite what Allah has commanded to be united, and fear their Lord, and apprehend the evil of the account.
Talal Itani
(13:21) And those who join what God has commanded to be joined, and fear their Lord, and dread the dire reckoning.
Ahmed Raza Khan
(13:21) Those who unite what Allah has commanded to be united, and fear their Lord, and apprehend the evil of the account.
Wahiduddin Khan
(13:21) and those who join together what God has commanded to be joined, and fear their Lord and dread the harshness of the reckoning;
Safi-ur-Rahman al-Mubarakpuri
(13:21) And those who join that which Allah has commanded to be joined and fear their Lord, and dread the terrible reckoning.
Ali Quli Qarai
(13:21) and those who join what Allah has commanded to be joined, and fear their Lord, and are afraid of an adverse reckoning
Hasan al-Fatih Qaribullah and Ahmad Darwish
(13:21) who join together what Allah has bidden to be united; who fear their Lord and dread the evil reckoning.
That is translated surah Ar Ra’d ayat 21 (QS 13: 21) in arabic and english text, may be useful.