They are strong against Unbelievers, (but) compassionate amongst each other

Tafseer Ibn Abbaas

“Muhammad is RasulAllah; and those who are with him are strong against Unbelievers, (but) compassionate amongst each other. Thou wilt see them bow and prostrate themselves (in prayer), seeking Grace from Allah and (His) Good Pleasure. On their faces are their marks, (being) the traces of their prostration. This is their similitude in the Taurat; and their similitude in the Gospel is: like a seed which sends forth its blade, then makes it strong; it then becomes thick, and it stands on its own stem, (filling) the sowers with wonder and delight. As a result, it fills the Unbelievers with rage at them. Allah has promised those among them who believe and do righteous deeds forgiveness, and a great Reward.” (al-Fath 49/28)

(Muhammad is RasulAllah) and this without the witness of Suhayl Ibn 'Amr. (And those with him) i.e. Abu Bakr, the first who believed in him and called the disbelievers with him to the religion of Allah (are hard against the disbelievers) this refers to 'Umar Ibn al-Khattab who was tough with the enemies of Allah, strong in the religion of Allah and a defender of Allah's Messenger (and merciful among themselves) and dutiful towards each other; this refers to 'Uthman Ibn 'Affan who was very dutiful and merciful towards the Muslims, and spent much of his money on them. (Thou (O Muhammad) seest them bowing) in prayer (and falling prostrate (in worship)) this refers to 'Ali Ibn Abi Talib who abundantly bowed and prostrated in prayer, (seeking bounty) reward (from Allah and (His) acceptance) acceptance of their Lord through Jihaad; this refers to Talhah and al-Zubayr who were very hard on, and tough with, the disbelievers. (The mark of them is on their foreheads from) the sign of their staying awake is on their faces from (the traces of prostration) from repeated prostration at night; this refers to Salman al-Farisi, Bilal, Suhayb and their fellow believers. (Such is their likeness) their description (in the Torah and their likeness) and their description in (in the Gospel like as sown corn) this is the Prophet (pbuh) (that) Allah (sendeth forth its shoot) i.e. Abu Bakr, the first to believe in him and the first to face the enemies of Allah (and strengtheneth it) and assists him; this is 'Umar who assisted the Prophet (pbuh) with his sword against the enemies of Allah (and riseth firm) He became strong with the wealth of 'Uthman which he used in Jihaad in the way of Allah (upon its stalk) and spread his message among Quraysh through 'Ali Ibn Abi Talib, (delighting the sowers) the Prophet (pbuh) was pleased with Talhah and al-Zubayr (that He may enrage the disbelievers with (the sight of) them) by means of Talhah and al-Zubayr. It is also said that from Allah's saying (Muhammad is RasulAllah…) up to here was revealed in praise of those who took part in the swearing of allegiance at Ridwan and the sincere, obedient prophetic Companions in general. (Allah hath promised, unto such of them as believe) in Muhammad (pbuh) and the Qur'an (and do good works) and do acts of obedience in private between themselves and their Lord, (forgiveness) of their sins in this world and in the Hereafter (and immense reward) and abundant reward in the Garden'.