The meaning of the poet's statement: "And you think that you are their heir, but you have not *** tasted the hardship in supporting the Most Merciful. No, nor have you striven in His cause with the full measure of His striving *** in Allah, neither with hand nor with tongue"

The Shaykh :"And you think that you are their heir, but you have not *** tasted—what they tasted—and you have not tasted the hardship in supporting the Most Merciful"
This means: Do you think that you are the heir of the Messenger (peace and blessings be upon him) when you have not tasted what they tasted? If you think so, then your hope has failed, for inheritance entails receiving everything that the deceased left behind in terms of calling, action, patience in the face of hardship, and deeming the entire world cheap in order to realize this call. This is the inheritance. So do you think that you are their heir when you have not tasted the hardship in supporting the Most Merciful? If your hope is such, then your hope has failed.
"No, nor have you striven in His cause with the full measure of His striving in Allah, neither with hand" This means you have not striven "neither with hand nor with tongue", and you wish to be the heir of the Messenger of Allah (peace and blessings be upon him)? No. If you wish for this, or think that you are his heir, then your hope has failed.