bibhrat svāṁ pauruṣīṁ tanum
tam — him (Lord Śiva); aviklavam — without being agitated by the incident that had taken place; avrīḍam — without being ashamed; ālakṣya — seeing; madhu-sūdanaḥ — the Supreme Personality of Godhead, who is known as Madhusūdana, the killer of the demon Madhu; uvāca — said; parama-prītaḥ — being very pleased; bibhrat — assuming; svām — His own; pauruṣīm — original; tanum — form.
Seeing Lord Śiva unagitated and unashamed, Lord Viṣṇu [Madhusūdana] was very pleased. Thus He resumed His original form and spoke as follows.
Although Lord Śiva was aghast at the potency of Lord Viṣṇu, he did not feel ashamed. Rather, he was proud to be defeated by Lord Viṣṇu. Nothing is hidden from the Supreme Personality of Godhead, for He is in everyone’s heart. Indeed, the Lord says in Bhagavad-gītā (15.15), sarvasya cāhaṁ hṛdi sanniviṣṭo mattaḥ smṛtir jñānam apohanaṁ ca: “I am seated in everyone’s heart, and from Me come remembrance, knowledge and forgetfulness.” Whatever happened had taken place under the direction of the Supreme Personality of Godhead, and therefore there was no cause to be sorry or ashamed. Although Lord Śiva is never defeated by anyone, when defeated by Lord Viṣṇu he felt proud that he had such an exalted and powerful master.