A Closer Look at the Tawarruk Posture

Shaykh Ibn ʿUthaymīn (may Allāh have mercy on him) was asked in Liqāʾ Al-Bāb Al-Maftūḥ: “When does a person praying sit in the posture of tawarruk during the prayer, and in which prayers?” He replied: “Tawarruk is performed in the final tashahhud of every prayer that contains two tashahhuds; that is, the last rakʿah of Maghrib, the last rakʿah of ʿIshāʾ, the last rakʿah of ʿAṣr, and the last rakʿah of Dhuhr. As for two-rakʿah prayers, such as Fajr, as well as the regular Sunnah prayers, there is no tawarruk in them. Thus, tawarruk is in the final tashahhud of every prayer that has two tashahhuds.” Tawarruk has been reported in three forms: 1⃣. That one lays the left leg flat, keeps the right foot upright, brings both feet out to the right side, and places the buttocks on the ground. This is indicated by the ḥadīth of Abū Ḥumayd al-Sāʿidī (may Allah be pleased with him), in which he said: ((فَإِذَا جَلَسَ في الرَّكْعَتَيْنِ جَلَسَ علَى رِجْلِهِ اليُسْرَى، ونَصَبَ اليُمْنَى، وإذَا جَلَسَ في الرَّكْعَةِ الآخِرَةِ قَدَّمَ رِجْلَهُ اليُسْرَى، ونَصَبَ الأُخْرَى وقَعَدَ علَى مَقْعَدَتِهِ)) “When he sat in the two rakʿahs, he would sit on his left leg and keep the right foot upright. And when he sat in the final rakʿah, he would advance his left leg, keep the right foot upright, and sit on his buttocks.” [Al-Bukhārī - 828] 2⃣. That one lays both feet flat, brings them out to the right side, and places the buttocks on the ground. This is indicated by the ḥadīth of Abū Ḥumayd al-Sāʿidī (may Allah be pleased with him), in which he said: ((حتَّى إذا كانتِ السَّجدةُ الَّتي فيها التَّسليمُ أخَّرَ رجلَهُ اليسرى وقعدَ متورِّكًا على شقِّهِ الأيسرِ)) “Then, when he was in the prostration after which the salām is given, he moved his left leg back and sat in tawarruk on his left side.” [Abu Dāwūd - 729] 3⃣. That one lays the right foot flat, inserts the left foot between the thigh and shin of the right leg, and places the buttocks on the ground. This is indicated by the ḥadīth of ʿAbdullāh ibn al-Zubayr (may Allah be pleased with them both): ((إِذَا قَعَدَ فِي الصَّلاَةِ جَعَلَ قَدَمَهُ الْيُسْرَى بَيْنَ فَخِذِهِ وَسَاقِهِ وَفَرَشَ قَدَمَهُ الْيُمْنَى)) “When he (ﷺ) sat in the prayer [for the final tashahhud] he would place his left foot BAYNA his thigh and his shin and lay his right foot flat.” [Muslim - 579] What is intended by "BAYNA" in this final hadith❓⤵️