The Quran

وَمَن أَظلَمُ مِمَّنِ افتَرىٰ عَلَى اللَّهِ كَذِبًا ۚ أُولٰئِكَ يُعرَضونَ عَلىٰ رَبِّهِم وَيَقولُ الأَشهادُ هٰؤُلاءِ الَّذينَ كَذَبوا عَلىٰ رَبِّهِم ۚ أَلا لَعنَةُ اللَّهِ عَلَى الظّالِمينَ

Muhammad Asad

And who could be more wicked than they who attribute their own lying inventions to God?¹ [On the Day of Judgment, such as] these shall be arraigned before their Sustainer, and those who are called upon to bear witness [against them]² shall say, "It is they who uttered lies about their Sustainer!"³ Oh, verily, God's rejection is the due of all evildoers⁴

This is a refutation of the contention of the unbelievers that the Qur'an was composed by Muhammad himself (cf. verse 13 above as well as 10:17) and thereupon blasphemously attributed to God.
Lit., "the witnesses". Most of the earliest authorities take this to mean the recording angels, while others (e.g., Ibn 'Abbas, as quoted by Baghawi) relate it to the prophets, who, on the Day of Judgment, will be called upon to testify for or against the people to whom they were sent. The latter interpretation is supported by Ad-Dahhak (quoted by Tabari and Baghawi) on the basis of 16:84, where witnesses "out of every community" are mentioned - an expression which can obviously refer only to human beings.
Or: "against their Sustainer".
The term la'nah - which is usually, but inexactly, translated as "curse" - is in its primary meaning synonymous with ib'ad ("alienation", "estrangement" or "banishment") in the moral sense; hence it denotes "rejection from all that is good" (Lisan al-'Arab) and, with reference to God, the sinner's "exclusion from His grace" (Manar II, 50).