It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) was asked which of the two terms Musa (peace be upon him) completed. He (peace and blessings be upon him) said: "The longer of the two and the purer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المساقاة / 11638