Tafsiran Ester 2:21: Rashi & Malbim

To assault. To give him poison to drink.²⁰Ibid. 13b. According to Targum they planned to poison Esther and to murder Achashveirosh with a sword.

The Questions:
Why did it mention here that Mordekhai sat at the gate of the king, when it already mentioned it above?

In those days: Before it comes to the story of the distress that the Jewish people experienced, it 'had the cure precede the injury, to teach that the injury is not in order to injure but rather in order to heal. This is like one who draws blood, who first prepares those things needed to temper and stop the flow of blood and to strengthen [the patient] after he draws [the blood]. And it is about this that it is stated (Exodus 15:26), "every sickness that I brought upon Egypt, I will not bring upon you, for I am the Lord, who heals you." Meaning to say, I will not place the sickness upon you with the same intention that I placed it upon Egypt, such that the main intent was in order to injure the evildoer. Rather I will place the sickness [upon you], from the angle that "I am the Lord, who heals you." And from that angle, He had the cure precede the injury; since [the former] is the main intent. Hence after He prepared the first preparation that God prepared against the breaking of His nation - in that which He arranged for them a sister in the house of the king and made it that Esther would wear the royal crown - it recounted the second preparation, in that which He prepared a merit and [source for] kindness towards Mordekhai in the house of the king, that which he saved [the king] from being killed. And it had precede before that story, that which Mordekhai sat at the gate of the king, for two reasons: The first was that it aroused the jealousy of the guards of the threshold. For their anger was aroused by Mordekhai sitting in pomp and circumstance while they stood on their feet to guard the threshold, in the way of [simple] guards. The second was that from this very cause, God caused Mordekhai to sit at the gate of the king, so that he would know about the anger of the officers. And in the way that Mordekhai's sitting at the gate was a cause for the Jewish people's distress - since Haman was taunted by this - it was itself a cause for their redemption. And this is the first miracle that God did [here]: That Mordekhai should be found there, and that was a cause for the cure for the future injury. (The second miracle was) that Bigtan and Teresh were angered, whereas men checked for their love of the king are chosen for this guardianship. But God caused that they would get angry for nothing. For since they were [just] officers, why should they be jealous of Mordekhai's status? Thirdly, the actual event, that they sought to take up their hand against the king of such stature: For if it happens that ministers have the temerity to rebel against their king, that is because they expect to crown one of themselves; it does not happen that two officers would do this, since they know that it will [cost them] their lives.