Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(And when he would have fallen upon the man who was an enemy unto them both) i.e. the Copt, (he said) i.e. the Israelite said: (O Moses! Wouldst thou kill me) today (as thou didst kill a person) a Copt (yesterday. Thou wouldst be nothing but a tyrant) a murderer (in the land) of Egypt, (thou wouldst not be of the reformers) of the pious who enjoin good and forbid evil.
But when (fa-lammā an: an is extra) he was about to strike the man who was an enemy to both of them, to Moses and the one seeking his help, he, the one seeking help, supposing that Moses was about to strike him, because of what he [Moses] had said to him, said: ‘O Moses, do you want to slay me just as you slew a soul yesterday? You merely want to be a tyrant in the land, and you do not want to be of the reformers’. The Egyptian heard this and realised that the slayer had been Moses. Thus he hurried off to Pharaoh to inform him of this. Pharaoh then ordered slaughterers to slay Moses, and they set off in his direction.
(he became afraid in the city) meaning, of the consequences of his action,
(looking about) means, turning around and watching out, waiting for the consequences of his action to befall him. He went out and about, and saw the man who sought his help the day before, fighting with another Coptic. When Musa passed by him, he called for his help again, against this other Coptic. Musa said to him:
إِنَّكَ لَغَوِىٌّ مُّبِينٌ
(Verily, you are a plain misleader!) meaning, `you obviously lead people astray and are very evil.' Then Musa intended to attack that Coptic, but the Israelite -- because of his own cowardice and weakness -- thought that Musa wanted to hit him because of what he had said, so he said, in self-defence --
(O Musa! Is it your intention to kill me as you killed a man yesterday) Nobody except him and Musa, peace be upon him, knew about it, but when the other Coptic heard this, he took the news to Fir`awn's gate and told him about it. So Fir`awn came to know of it, and he became very angry and resolved to kill Musa, so he sent people after him to bring him to him.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
That is, "You seem to be a quarrelsome man:you have daily a new quarrel with one or the other person."
Here, the Biblical version is different from the Qur'anic. The Bible says that the fight on the next day was between two Israelites, but according to the Qur'an this fight also was between an Israelite and an Egyptian. This second version seems to be credible, for the manner in which the secret of the murder of the first day became known, as is being mentioned below, could be possible only if a member of the Coptic community had come to know of the matter. An Israelite's knowledge of it could not be so treacherous: he could not have gone to inform the Pharaonic government of such a heinous crime committed by the prince, who was a great supporter of his own community.
The one who cried out was the same Israelite whom the Prophet Moses wanted to help against the enemy. When after scolding and rebuking him, he turned to assault the Egyptian, the Israelite thought that Moses was going to strike him; therefore, he raised a hue and cry and disclosed the secret of the previous day's murder by this own folly.
This happened when in the second day's fight, the secret of the murder became known and the Egyptian informed the authorities about the case accordingly.