مصنف ابن ابي شيبه
Musannaf Ibn Abi Shaybah
سجود السهو والعمل في الصلاةProstration of Forgetfulness and Actions in Salah
في الرجل يصلي (فلا يدري) زاد أو نقصIf Someone Prayed but Does Not Know How Many Rak‘ahs He Prayed, What Should He Do?
Hadith 4470
٤٤٧٠ - حدثنا ابن فضيل عن (خصيف) (١) عن (أبي عبيدة عن عبد اللَّه) (٢) قال: إذا شك أحدكم في صلاته فليتحر أكثر (ظنه) (٣) فليبن عليه فإن كان أكثر (ظنه) (٤) أنه صلى ثلاثًا فليركع ركعة (ويسجد) (٥) سجدتين وإن كان (ظنه) (٦) أربعا فليسجد سجدتين (٧).
Hazrat Abdullah says that if any of you has doubt about the number of units (rak‘ahs) in prayer, then after reflection, act upon what is most likely. If his predominant assumption is that he has prayed three rak‘ahs, then he should pray one more rak‘ah and perform sajdah sahw. If his predominant assumption is that he has prayed four rak‘ahs, then at the end he should only perform sajdah sahw.
