Glad tidings of a painful torment
Those who disbelieve in the signs of Allah and kill the prophets without right and kill those who order justice from among the people - give them tidings of a painful punishment.
[Qur'aan 3:21]
The word used in this Noble Verse is bashshir [give glad tidings]. It is used to give news of that which one loves. In this case it has been used to give news of a painful torment. The explanation presented for this is that they used to believe that what they are doing is good. So in accordance with that, they expected glad tidings. Thus, it was said to them: Your glad tidings, based on what your belief necessities, is a painful torment. Thus, the word which is used [give glad tidings] is based on their belief that they are doing good.
In reality glad tidings are given when one is informing someone of something which will make the person happy. However, in this Verse it has been used in a manner which is opposite to what it is meant to be used for. Here it is used to give information of a painful torment which would make one sad. Scholars have named this usage tahakkumiyyah [mocking, sarcastic, scornful] because giving resemblance to an opposite with its opposite is not understandable except when it is used in the meaning of tahakkum [mockery, scorn, sarcasm, derision].
Reference(s):
'ahkaam al-Qur'aan lii Ibn al-'Arabi
Volume 1. Page 26