Tafsir Ibn Kathir -> Surah As-Saff -> Muslims are always the Natural Supporters of Islam

Allah the Exalted orders His faithful servants to be Allah's supporters at all times, in all their statements and actions, sacrificing their selves and wealth. Allah orders them to accept His and His Messenger's call, just as the disciples said to Prophet `Isa when he said,

﴿مَنْ أَنصَارِى إِلَى اللَّهِ﴾

(Who are my helpers (in the cause) of Allah) meaning, `who will support me in conveying the Message of Allah, the Exalted and Most Honored'

﴿قَالَ الْحَوَرِيُّونَ﴾

(The Hawariyyun said:) in reference to the followers of `Isa, peace be upon him,

﴿نَحْنُ أَنصَـرُ اللَّهِ﴾

(We are Allah's helpers) meaning, `we will support you with regards to the Message you have been sent with and will help you convey it.' Whereby, `Isa sent the disciples to the various areas of Ash-Sham to call the Greeks and the Israelites to Islam. Similarly, during the days of Hajj, Allah's Messenger used to ask,

«مَنْ رَجُلٌ يُؤْوِينِي حَتْى أُبَلِّغَ رِسَالَةَ رَبِّي؟ فَإِنَّ قُرَيْشًا قَدْ مَنَعُونِي أَنْ أُبَلِّغَ رِسَالَةَ رَبِّي»

(Who will support me in conveying the Message of my Lord Verily, the Quraysh have prevented me from conveying the Message of my Lord.) Allah the Exalted and Most Honored raised Al-Aws and Al-Khazraj to support the Prophet. They were the residents of Al-Madinah who gave the pledge to him and supported him, vowing to protect him from mankind and the Jinns if he migrated to them. When he migrated to them with his Companions, they fulfilled their vow to Allah. This is the reason why Allah and His Messenger called them, Al-Ansar, the Supporters. The name became synonymous with them. May Allah be pleased with them and please them, as well.