During their lifetime, my parents directed that a plot of arable land they own should be allocated, as their…

During their lifetime, my parents directed that a plot of arable land they own should be allocated, as their legitimate share of one-third of the estate after their death, to pay for the expenses arising from their funeral, others relating to the performance of prayers and fasting they may have missed during their lifetime, and the like. Being their only son, and since they had no cash left after their death, I paid all the expenses from my own pocket. Is it permissible for me to retrieve what I spent from the share of one-third they have provided for in their will?