"As a justification or a warning," meaning: God justifies Himself by it before His servants and warns them.
Al-Suddi said: The meaning is: an excuse and a warning, and the [extra] alif is a connector.
﴿عذرا أَو نذرا﴾ أَيْ: يَعْذِرُ اللَّهُ بِهِ إِلَى عِبَادِهِ وَيُنْذِرُهُمْ.
قَالَ السُّدي: الْمَعْنَى: عُذْرًا وَنُذْرًا، وَالْأَلِفُ صِلَةٌ.
