What is the ruling on saying: "O Lord: I beg You" in supplication? And is it permissible to supplicate by saying: "O Lord, send me tomorrow or today someone to propose to me, and make him my destiny, for You are capable of all things"? And is that considered hastiness in supplication?

There is nothing to prevent supplicating with the aforementioned phrases, and asking for the supplication to be answered on the same day or later is possible and legitimate. The blameworthy haste in supplication is for the servant to say: "I supplicated but was not answered," and then abandon supplication. The Prophet, peace and blessings be upon him, warned against this, saying: "The supplication of any one of you will be answered as long as he does not supplicate for a sin or cutting off ties of kinship, and as long as he does not become impatient." It was said: "O Messenger of Allah, what is impatience?" He said: "He says: 'I supplicated and I supplicated, but I did not see it being answered,' so he becomes disheartened and abandons supplication." Supplication is one of the best means to achieve what is sought from Allah Almighty.