On this issue, Dr. Rajab Abu Mleeh, Ph. D. in sharia said ‘that the difference between the obligatory Prayers and the supererogatory prayers whether it is mu’akkadah (affirmed) such as Witr ones or not is that a person who does not perform the obligatory Prayers deserves punishment while there is no punishment for he who does not perform the supererogatory prayers including the Witr ones.
Thus, if a Muslim limits himself to performing the obligatory prayers, there is no punishment to be afflicted on him. This is the rule of the majority of the scholars.
However; some scholars opine that he who abandons Witr prayer deserves punished since they consider it as an obligatory prayer, but the first opinion is the preponderant one.
Any way, a Muslim should be keen on offering Sunnah prayers, for the simple fact that it’s the practice and tradition of the Prophet (peace and blessings be upon him). In addition to this, Sunnah (supererogatory) prayers entail great benefits and rewards.’