Commentary
Mentioned in the first verse (79) are taunts thrown at Muslims who gave away in charity on a voluntary basis (Nafli Sadaqat). It appears ؓ in the Sahih of Muslim that Sayyidna Abu Masud ؓ said: ` we had orders from Allah Ta` ala that we must give Sadaqah and, believe it, we used to do manual labor for that (that is, we had no money or thing with us. We used to take out that Sadaqah too from whatever we earned through this very manual labor). Thus, Abu 'Aqil offered Sadaqah to the measure of 0.5 Sa` (approximately 1.75 kilos). Then, someone came and gave a little more than that. The hypocrites mocked at them for having brought something so insignificant in the name of Sadaqah. Allah never needs things like that. And whoever gave a little more in Sadaqah, they accused him that he had done it to show off before people. Thereupon, this verse was revealed.
Please note that, in the sentence: سَخِرَ اللَّـهُ مِنْهُمْ (mocked they are by Allah - 79), the word 'mocked' stands for 'punished for their mockery'.
In the second verse (80), there is a statement about the hypocrites. It has been addressed to the Holy Prophet ﷺ . He has been told whether or not he seeks forgiveness for them makes no difference - and no matter how many times he seeks forgiveness for them, they shall not be forgiven. A detailed explanation of this appears under the comments on verse 84: لَا تُصَلِّ عَلَىٰ أَحَدٍ مِّنْهُم (and never offer a prayer on anyone of them who dies) appearing a little later.