Assalaamu alaykum. I read here on islamweb that suggesting gambling to someone requires giving charity to make up for it, but what I did was joke about someone else on the matter. What I said was that someone else (who had succeeded against the expected outcome) should have bet against the person who said that she could not do it. I did not actually recommend anyone to gamble but made a joke that someone else should have made the bet. What is the ruling on this?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger. 

We did not find any statements from the scholars about the specific case that you mentioned. It seems - and Allaah knows best - that it is not included in the hadeeth about gambling that you are referring to. Rather, it is related to calling others to engage in gambling in the present time, and it is forbidden for the Muslim to invite others to commit what is unlawful. Al-Haafith Ibn Hajar wrote, “...here (in this hadeeth), he has already invited him to sin; as gambling is unanimously prohibited, so inviting others to gambling is also prohibited...” [Fat-h Al-Baari]

In this case, the person is inviting another to do what it is possible for him to do because it is related to the present time, as stated above. This is different from what you mentioned, which is a past incident, and there is no way to carry it out now.

It should be noted, though, that making such a remark, that someone should have gambled and wishing that he had done so, is not free from sharee'ah violations. In any case, there is no room for joking when it comes to prohibited acts.

Allaah knows best.