What is wrong with the poet's saying: "How can I remember Him when I do not forget Him?" and "And Allah knows that I do not forget Him"? And what is the ruling on uttering this poetry if great love for Allah is intended thereby?

Poetry, by its nature, contains exaggeration and expansion of expressions, and it is not to be judged by literal scrutiny unless its meaning contradicts Islamic law. There is no legal impediment in these verses if they are said about a creature. However, saying them about Allah is not appropriate because their meanings are not befitting of Allah, the Almighty. There are verses of praise for a creature that can be said about Allah, such as the saying of Ibn Kathir: "O You in whom I seek refuge for what I hope for...", and the saying of Abu Firas: "Would that You were sweet, though life be bitter...".