It is narrated from Hazrat Thawban (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Remain steadfast, for you will never be able to encompass all deeds. However, know that your best deed is prayer, and only a believer maintains regular ablution.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 22436
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد منقطع، سالم لم يسمع من ثوبان، وقد توبع