Hashem speaks to Moshe and tells him: EMOR EL HAKOHANIM … VE’AMARTA ALEHEM, “ speak to the Kohanim … and you shall say to them.” (Lev. 21’1) The Talmud and Rashi and almost all the Biblical commentaries ask why the repetition of “speak” and “say”. This duplication is strange for the Torah.
There was a famous preacher in Europe who was known as the Maggid of Dubna, the Preacher from the city of Dubna. He had a unique way of expounding his message. He would always create a story that would elucidate his theme. He told the following example to explain our passage.
A doctor tells a patient to maintain a special diet to prevent a harmful medical condition. This is preventative advice. The person does not heed the warning and gets sick. The doctor then repeats the advice with the same warning. This time the patient follows the advice.
In a similar fashion, Hashem gives the directive but warns them to accept it on the first decree, but He repeats it in case they do not accept the original instruction. This is a more stern manner of saying be sure to pay attention to the direction. In life we find many times people are given good advice but they ignore it. Only after the consequences befall do they start heeding the warnings and the counsel. We could save ourselves much trouble and anguish if we listen the first time.