﴿ ٱلْحَقُّ مِن رَّبِّكَ فَلَا تَكُن مِّنَ ٱلْمُمْتَرِينَ ﴾

“[This is] the truth from thy Sustainer; be not, then, among the doubters!”

The truth is from your Lord al-haqqu min rabbik the predicate of a missing subject which is implied to be amr ‘Īsā ‘the matter concerning Jesus’; be not of those who waver those who are uncertain about it.