What is intended by "God knows, and you know not"?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. It means that Allah knows the affection each of them has for the other. [Ibn ʿAbbās, al-Ḍaḥḥāk]
2. It means that Allah knows what is in your best interests, both in the short term and the long term. [Al-Zajjāj and others]