(a) Sayyiduna Jabir bin Samurah (may Allah be pleased with him) relates: When we prayed behind the Messenger of Allah (peace and blessings be upon him), we would say, pointing with our index fingers: 'As-salamu alaykum, as-salamu alaykum' (Peace be upon you, peace be upon you). The Prophet (peace and blessings be upon him) said to us: "What is the matter with people who gesture with their hands in prayer as though they were the tails of restive horses? Is it not enough for one of them" or he said: "for one of you to place his hand on his thigh and then give the salam to his right and to his left?"
(b) Imam Muslim (may Allah have mercy on him), in his Sahih, in the hadith of Mis'ar bin Kidam, said: "Then he should give the salam to his brother on his right and on his left."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2981