﴿ إِذْ دَخَلُوا۟ عَلَيْهِ فَقَالُوا۟ سَلَٰمًۭا ۖ قَالَ سَلَٰمٌۭ قَوْمٌۭ مُّنكَرُونَ ﴾

“When those [heavenly messengers] came unto him and bade him peace, he answered, “[And upon you be] peace!” - [saying to himself,] “They are strangers.””

When idh is an adverbial qualifier of hadīthu dayfi ‘the story of the guests’ they entered upon him and said ‘Peace!’ — in other words they said these very words. He said ‘Peace!’ — also these very words — These are an unfamiliar folk whom we do not know — he said this to himself qawmun munkarūna is the predicate of an implicit subject such as hā’ūlā’i ‘these are’.