It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Seek help for standing (in prayer) at night through the midday nap, and seek help for fasting during the day through eating the pre-dawn meal (suhur)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11575