It is narrated from Abdullah bin Dinar that he saw Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) urinating while standing.
(b) We have narrated here reports of urinating while standing from Sayyiduna Umar, Ali, Sahl bin Sa'd and Anas bin Malik (may Allah be pleased with them).
This weakens the hadith of Abd al-Karim.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 494