Abdullah bin Amr bin As reported,

Word reached the Prophet ﷺ that I was fasting continuously and praying through the night. He either sent for me or I met him, and he asked, "Have I not been told that you fast without breaking your fast and that you pray all night? Fast and break your fast, pray and sleep, for your eye has a right over you, and your soul and your family have a right over you."I said, "I am strong enough for that."He said, "Then fast the fast of Dawud ."I asked, "And how was that?"He said, "He would fast one day and break his fast the next, and he would not flee when he met the enemy."I said, "Who can grant me the strength for this, Prophet of Allah?"Ata said, "I do not know how he mentioned fasting perpetually."The Prophet ﷺ said, "He has not fasted who fasts every day," saying it twice.

عن عبد الله بن عمرو، قال

بلغ النبي ﷺ أني أسرد الصوم، وأصلي الليل فإما أرسل إلي وإما لقيته، فقال: ألم أخبر أنك تصوم ولا تفطر وتصلي؟ فصم وأفطر، وقم ونم، فإن لعينك عليك حظا، وإن لنفسك وأهلك عليك حظا. قال: إني لأقوى لذلك. قال: فصم صيام داود عليه السلام. قال: وكيف؟ قال: كان يصوم يوما، ويفطر يوما ولا يفر إذا لاقى. قال: من لي بهذه يا نبي الله؟ قال عطاء: لا أدري، كيف ذكر صيام الأبد. قال النبي ﷺ: لا صام من صام الدهر مرتين.