Halakhah su Ecclesiaste 4:7

It is written: "Guard your feet when you walk to the house of God."⁴Ecclesiastes 4:7. Our Sages, of blessed memory, explain that "your feet," refers to the openings that are near the legs.⁵Maseches Berachos 23. Therefore, before praying you must check if you need to relieve yourself. If you feel even the slightest urge for relief, you are forbidden to pray. It is even forbidden to study Torah when the body is feculent until you relieve yourself. If, however, you prayed when you had the urge to relieve yourself, if you approximated that you could have restrained yourself the length of time it takes to walk a parsah (an hour and a fifth) your prayer is valid. If you could not have restrained yourself even though you have already prayed, your prayer is an abomination and you must pray again.⁶This does not apply if you only had the need to urinate. See Magen Avraham 92:1. Some authorities hold that if you can restrain yourself for the period of a parsah, you may even begin praying in this condition. You may rely on this opinion in a situation where if you relieve yourself the time limit for prayer will elapse. See chapter 18, paragraph 16.